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MARYLAND GEOLOGICAL SURVEY. 

WM. BULLOCK CLARK, State Geologist. 



THE ^^^c 

BUILDING AND DECORATIVE STONES 



OF 



MARYLAND 




Containing an 

Account of their Properties and Distribution. 



BY 



GEORGE P. MERRILL AND EDWARD B. MATHEWS. 



(Special Publication, Volume II. Part D.) 



THE JOHNS HOPKINS PRESS. 
Baltimore, October, 1898. 






^-^4^ 



/y 



o 
I 
o 



PART II 

THE BUILDING AND DECORATIVE STONES 
OF MARYLAND 

BY 
GHORGE P. MERRILL and EDWARD B. MATHEWS 



CONTENTS 

IMCK 

PART II. THE BUILDING AND DECORATIVE STONES OF MARYLAND. 
Bv Gkougk p. .Mkiiiiii.i. .v.nd Enw.\ni) B. Matiikws. 

THE PHYSICAL, CHEMICAL, AND ECONOMIC PKOl'EKTIES l)l' 111 II.D- 

IN(i STONES. Bv (JKiimii; P. Mehhii.i 4 7 

GESEKAL CoNSIDEU.tTlOSS 47 

Classification 47 

Diversity of Resources 4>i 

Geological Conditions 4'.i 

Formation and Present Position 4!) 

Variability in Composition and Structure .51 

Position of Beds and Expense of Quarryinu' .5^' 

Thickness of Beds .')4 

Beddiii!!; and Jointini;- .5.'; 

Efl'ects of Weathering and Erosion .57 

Color of Rocks (i3 

Geological Age 04 

The Strength of Stones 0.5 

Geographic Distribution of Stone in the State 65 

Methods of Quarrying and Working 68 

Relation of Maryland to Other Producing Areas SO 

Preliminary Oeueralitii's 80 

Kinds of Stone Produced by Other States 81 

WEATUEUl.Mi OF Bl'11,I>1NG STONE 00 

Methods of Testing Buii-ding Stone Oil 

Tests to ascertain Permanence of Color 00 

Tests to ascertain Resistance to Corrosion lOli 

Tests to ascertain Hesistiince to Abrasion 101 

Tests to ascertain Absorptive Powers . . lO'J 

Tests to ascertain Resistance to Ereeziug 104 

Tests to ascertain Ratio of E.\pansion and Contraction lO'.i 

Tests to ascertain the Fireproof Qualities of Stone Ill 

Tests to ascertain Resistance to Crushing Wi 

Tests to ascertain Elasticity of Stone 115 

Tests to ascertain Resistance to Shearing 117 

Tests to ascertain the Specific Gravity 110 

The testing of Roofing Slates 110 

Strength and Toughness 120 

Corrosion by .Vcids 121 

Softness or Capacity to Resist Abrasion 121 

Conclusions 121 



) CONTENTS 

PAGE 

AN ACCOU.VT OF THE CHARACTER AND DISTRIBUTION OF MARY- 
LAND BUILDING STONES, tooetheu with a History of the 
Qi"AKRViNr; Industry, By Euward B. Mathews 125 

iNTIiODrCTIOX 125 

Previous Publicatious 136 

Bibliosrapliy 131 

The Qi'arries of Maryland 136 

Oranites and Gneisses 136 

Geological Occurrence 137 

Discussion of Individual Quai-rv Areas 138 

Granites 13S 

Port Deposit 138 

Frenchtown 146 

EUicott City 147 

Woodstock 150 

Gnilford 1 56 

Minor Areas 158 

Gneisses 160 

Jones' Falls 161 

Gwynn's Falls 166 

Gabbro 168 

Ampliibole Schist 169 

Marbles and Limestones 169 

JIarbles 171 

Cockeysville and Texas 173 

Marbles of Carroll County 185 

" Potomac Marbles." 187 

Serpentine or " Verde Antique." 193 

Limestone 197 

Sandstones 199 

Triassic Sandstones 199 

Paleozoic Sandstones 308 

Micaceous Sandstones of Eastern Maryland 213 

Slate 314 

General Disiri lint ion 314 

Peach Bottom Area 315 

Ijanisville Area 331 

The Building Stone Trade 333 

Collection of Statistics 333 

Annual Production in Maryland 334 

Prices, Was-es, etc 337 



THE PHYSICAL, CHHMICAL, AND ECONOMIC 
PROPERTIES OF BUILDING STONES 

BY 

GEORGE P. MHRRll.L 



GENERAL CONSIDERATIONS. 

There arc, in Maryland, four general classes of stone possessing siich 
natural qualities as to make them available for constructive as well as 
ornamental pnrjiose?. These four are (1) the granites and gneisses, 
(2) the common limestones and dolomites; the marbles (eiystalline 
limestones and dolomites): (3) the sandstones and conglomerates, and 
(4) the argillites or slates. In addition to these there are certain basic 
eruptive rocks Tised locally for pnrjjoses of rough constnu-tion, and 
other altered forms of eiiiptive rocks like the serpentines, which in 
some instances are of such color and texture as to render them of value 
as verdantique marbles. The individual characteristics of each of 
these groups will be taken up in detail later; in this preliiuinary 
chapter we will dwell rather on their geographic distribution in the 
state; and since this is due to geological causes, we will touch first 
upon the matter of their origin and the agencies which have been 
instrumental in making them accessible. 

Classificatiox. 

From a geological standpoint all those rock types mentioned above 
may be classed as (1) cniptives, (2) clastic sedimeutaries, and (3) meta- 
morphics. The tirst include only those types which, like granite and 
the gabbros, have resulted from the crystallization, and subsequent 
exposure tln-ough erosion, of molten matter forced up into overlying 
strata. The second includes those rocks made up cither of fragments 
of older, pre-existing rocks, or of calcareous materials derived from the 



48 



THE liUILDIAU AXD DECORATIVE STO^'ES 



shells and stony skeletons of niollnsks, corals and other lime-secretinji- 
marine animals. They are in short indurated beds of clay, sand, 
gravel or calcareous mnd which have been deposited on ancient sea- 
liottiims. The third i;'run}i comprises rocks of both the first and 
second, which have been changed from their original condition 
through processes known as metamorphic, and which usually accom- 
pany such foldings of the earth's ci'ust as are incideutal to the pro- 
<luetion nf uKuintain chains. 

DivEESirv OF Eesoueces. 

Such being the case it is evident at once that the more diversified 
the landscape by hills and \'alleys, the greater mil probably be the 
variety of materials. In regions abounding with mountain chains 




^i_.:.i^ 



Fui. 1. — I(le:il ti>;iiii.' showiiii;- structure of the earth's i-'rust (utter U. S, G. S.). 



we may look for a greater variety of materials than in the le-\-el plains. 
This not merely because such have here been formed, but because 
through uplift and erosion they have been made accessible. 

By reference to a map of the United kStates it will be seen that the 
state of Maryland, in an east and west direction, stretches almost 
entirely across the Appalachian Mountain System. It occupies such 
a position with reference to this uplift and the less distiirbed ai-eas 
to the east and west as to lead vis to expect a great diversity of mater- 
ials even had not actual exploitation already shown them to exist. 
There is indeed probably no state in the American T'nion of the same 
area, that can be made to show a greater diversity in geological 
resources. 



-manvl.vxu geological sirvkv 49 

Geological C'oxditioxs. 

In order to gain a satisfactory idea of the rclatiousliip of these 
various classes of rocks, let ns consider for a moment the diagram 
given helow. 

formation and peesent position. 

The oldest rocks of which we have knowledge, and wliich seem to 
form the floor npon wliich liave been built up all those since formed, 
are rocks of the gneissic and granitoid group. These, through super- 
ficial disintegration and decomposition, have yielded silts, sand^and 
gravels, which carried by stream action to the seas have been spread 
out in approximately horizontal layers to be once more consolidated 
into stony matter, and perhaps in part metamorphosed, as will be 
described later. Such being their method of formation, it is easy 



NOnTM MTN BlIlFPinrr CATOCTINMTN. r,„.o , n..-..T.. 

l/„ u IV BLUE RIDGE iHrn SUGAR LOAF MTN. 




Kio. 2. — Generalized section from Sugar Loaf Mountain to North Mountain 
(lifter Williams). 

to see that these later formed rocks would naturally lie in parallel 
beds, the oldest, or first formed, on the bottom and the youngest at 
the top. And as the character of the material forming these sedi- 
ments differed from time to time, both in texture and in chemical com- 
position, sometime? being mere clay, sometimes sand, gravel, ov 
calcareous matter, so it will be perceived these beds may differ, and 
wo may have in tlH> same horizontal series, sandstones, shales, lime- 
stones, slates and conglomerates. The character, thickness and lat- 
eral extent of such beds, vary almost indefinitely. As a rule, the 
beds of conglomerate are the least extensive, while the sandstones, 
limestones and shales may cover areas of many square miles. 

That these beds of stratified, or sedimcntaiy rocks as they are 
called, are not in all cases still lyino- horizontally, the oldest deeply 
buried and inaccessible, is due to the folding and faulting to which 
they have been subj.ectcd incidcntnl 1o the formation of the Appal- 



50 



THE BUILDING AND DECOEATIVE STONES 



achiau Mountains. Their present position is shown in Fig. 2, which ' 
represents an actual section across the State between Sngar Loai 
Mountain and North Mountain. 

Accompanying this uplifting there were in many mstances large 
quantities of igneous rocks forced between the older strata or into 
the rifts and fissures by which they were traversed, or m the form o± 
immense domeshaped masses beneath folds, as shown at R m the 
section. These cooled to foiin trappean rocks, diabases, pendotites 
and in some cases granites. 

But the -uplifting was productive of other effects than that ot 
merely rendering accessible. As is well known, pressure generates 
heat and heat accelerates chemical action. A series of chemical pro- 
cesses was thereby set in motion ^^•hich resulted in a more or less com- 
plete ehano-e in the stnicture and general textural features of the rocks, 
as well as,^in some cases, in color and in composition. Through these 
agencies many of the beds of limestone became converted mto mar- 
bles, the sandstones into schists and the argillites into cleavable slates, 
suitable for roofing purposes. 

In some instances this uplifting and metamorphism has gone on to 
such an extent as to practically ruin the stone for commercial pur- 
poses The reader can perhaps best gain an idea of what has occurred 
by takino' a pile of writin- paper or an ordinary magazine or paper- 
covered book, a half inch or more in thickness, andby pressing against 
the back and edges and throwing it into a /^^ shaped fold. 
By making first a pencil line directly across JJ Vv the edges at 
the end, i^t will be observed that, after th. folding, this line is no 
longer at right angles with the leaves, but cuts diagonally across 
them at an angle dependent upon the amount of folding. This 
means, of course, that the sheets of paper have moved over one 
another slightlv. Now fancy that each sheet of paper, or page of 
the book, as the case may be, represents a bed of stone, from a frac- 
tion of an inch to it may be several feet in thickness, and that all is 
weighted down by overlying rocks to such extent that the simple slip- 
ping of the bed^ one over the other as with the paper becomes a 
mat^ter of great difficultv. When then the folding takes place, it is 
accompanied bv more or less crushing and fracturing, and Imes of 



MARYLAND GEOLOGICAL SURVEY 



51 



A\-eakness, if not absolute rifts, arc opened. .Moreover, if the beds 
do not slip but remain themselves approximately stationary with 
relation to one another, it will readily be seen '^that those in the 
npper part of the fold will be subjected to a stretching process, per- 
haps even to the point of fracturing, while those in the lower portion 
will bo con-espondingly squeezed and enih^lud as shown in tli,. figure. 
Between these two extremes will be a zone practically unaffw^ted, 
and known to geologists as the zone of no strain. Now it is obvious 
that the condition of the material to be found in one of these folded 
areas will depend up.ui what portion of the fold is accessible. H 
erosion has exposed the materials in the zone of no strain {A C B) 




Folded rocks (:iftcr \au Rise). 



it may be good, but if only the superficial beds {D) or the very lowest 
{E) are accessible, the materials may be all so seriously shattered as 
to be full of joints, dry seams and other defects, so' as to render 
the production of blocks of large size an impossibility. Small sam- 
ples of great beauty may be found in abundance, but the beds as a 
whole are worthless. This condition of affairs actually exists in 
many parts of Maryland and Virginia, and in the latter state con- 
siderable sums of money have in one instance at least been lost in 
attempting to develop a quarry. 



VAKIABILITY IN COMPOSITIOX AND STRUCTURE. 

There are other geological features which are of importance to the 
quarryman. 

Stones which were laid down as sediments on seabottoms are more 



52 THE BUILDING AND DECORATIVE STOKES 

variable both in composition and structure than are those of erupti^•c 
ori-in This for the reason tliat the character of the sediments depos- 
ited from time to time, vaiy. We may thus have in the same vertical 
sectiou rocks varving from conglomerates to sandstones, layers of 
sandstone altei-nating vith shale or with limestone. Sound, firm beds 
of desiralile material may be separated from one another by layers 
of shale which are absolutely worthless; beds of white homogeneous 
marble may be interbedded with impure layers can-ying pynte and 
micaceous minerals which wholly ruin it for commercial purposes. 
In quarrying, all these matters have to be taken into consideration, 
since, as 'waste products they must be removed, and the proportions 
existing between such and the merchantable stone may he the sole 
factor In deciding whether any quany can or cannot be worked sue- 

c6ssiiAlly. 

Ao^ain, the amount of tilting and crushing beds have undergone 
duriitg the process of uplifting is an important item. If the beds lie 
nearly horizontally and (luarrying is commenced upon the upper beds, 
it is obvious that only one grade of material can be produced at a 
time Each layer, as it is passed through successively, as the quarry 
increases in depth, yields its own grade of material which may or 
may not agree with that above or below. This is the case m the 
quarries of brown sandstone in Connecticut. When a quarry is 
opened in a liiUside. or ravine, where a number of beds have been 
exposed through erosion, or on the upturned edge of beds steeply in- 
clined as in the sketch, it is obvious that the quarry may at the same 
time be producing a great variety of ,naterials. Some of the marble, 
quarries of Vermont, for instance, which are opened on such upturned 
edo-es, produce from the various l,eds which are being worked simul- 
taneously, marbles of pure white, clouded, dark veined, nght water 
blue and dai-k bluish or greenish tints, the colors being dependent 
upon the amount and character of the impurities in the original sedi- 
ments. 

POSITIOX OF BEDS AXD EXPEXSE OF QUABRYIXG. 

The position of the beds has, further, an important bearing on the 
cost .d- quarrvino.. It is self-evident that where the beds lie almost 
horizontally, 'and quarrving is resolved into merely cutting through 



MAIfYr.AM) GEOLOGICAL SURVEY 



53 




54 THE BUILDING AND DECOEATIVB STONES 

one bed after the other, as in the sand and limestone quarries of the 
upper Mississippi valk.y. The ^vork can be carried on comparatively 
cheaply, provided that there is not too much preliminaiT stripping 
(Plate' lY Fio- 1). When, however, the beds stand at high angle, 
or are exposed'only in a hillside, quarrying must be carried on either 
on a highly inclined floor, as in the quarries of gneiss north and west 
of Baltimore, or directly across the edge of beds, whereby considerable 
extra trouble and expense are involved. 

THICKNESS OF BEDS. 

In looking for new quarry sites, the geological structure of the 
countrv should always be taken into consideration. When the beds 




Pjp 5 — Diagram showing relation 



between thlcliness and exposure of beds. 



lie horizontally it is obvious that the character of any but the upper- 
most beds can be ascertained only by investigation in hi Isides and 
along the banks of ravines. Where they are highly mclmed, it is 
in inanv instances suflicient to explore superficially along a line a 
right angles with the lateral extension, or .infce of the beds, as it 
technically called, that is to say, to follow along the line A B m lig. 5. 
The character of the various beds exposed can thus be ascertained 
and when one sufficiently promising is found, its extent can be best 
made out by following it out .long the line of strike. 

Since the actual thickness of a bed of stone may be a ma ter of 
importance, it may be well to state how this can be best ascertamed. 



MARYLAND GEOLOGICAL SURVEY 55 

It is obvious that with hods iiu-liiu'd ;is in the figure, tlie width of 
exposure on the iuiniediate surface is vastly greater than that of the 
true tliiekness of the bed itself. In such cases the apparent thickness 
is greater the smaller the amount of inclination. 

Sir Archibald Gcikic, is his Text Book of Geology, gives the fol- 
lowing general rule to be followed when the inclination is less than 
45°, and it is in such cases that the greatest discrepancies exist. The 
real thickness of an inclined strata, or bed, may be taken to be 1/12 
of its apparent thickness for every five degrees of dip. That is, if, 
as in the sketch we have a series of beds outcropping on the surface 
along the line A B and dipping as shown, to the right, at an angle 
of 15°, the actual thickness of one of the beds, X Y, will not be the 
distance — say 100 feet — measured between these points, but 1/12 of 
100 multiplied by 3, or 25 feet. 

The amount of dip which beds may have and the character of the 
overlying rock should receive careful consideration before quarrying 
is commenced. In the case shown in tlie figure, if .Y — Y is the 
workable bed, it is evident at once that the quariy must sometime 
cease to be an open cut, and must then be followed underground. If 
the overlying rock forming the roof is soimd and strong, this can be 
done with comparati\-e safety by leaving occasional pillars for support. 
But if of a weak, or friable natiu'e, it must be continually 
removed by stripping, thus increasing the cost. It is fortunate tliat 
in the majority of cases the amount of area exposed on the immediate 
surface is so large that it is not necessary to follow the beds to great 
depths, though in Vermont some of the marble quarries are even now 
over 200 feet in depth and partake more of the nature of mines than 
quarries, as the word is commonly understood. Naturally such deep 
quarries are nuich more expensive to work since not only must the 
cost of hoisting both merchantable material and waste lie very con- 
isiderable, but steam pumps must be continiially at work to carry off 
th(^ water which would otherwise collect to a depth of very many 
feet, even filling the entire quarry to vithin a few feet of the surface. 

BEDDING AND .lOIXTING. 

Among the unaltered eruptive rocks there is a total absence of 
bedding planes or other like structural features, the rocks being homo- 



Ob THE BUILDING AND DECORATIVE STONES 

geneons and capable oi being worked with almost equal facility in 
any direction, presenting on all sides the same appearance. Such do, 
it is true, have two definite directions at I'ight angles with one another, 
along which they can be relied to split most readily. These are 
knoM-n as rift and grain, and though wholly inconspicuous to the 
ordinary observer, are readily detected by an experienced stone cutter. 
Bedded and stratified rocks, on the other hand, almost invariably 
present readily recognizable structural features. It rarely happens 
that an unaltered or even metamorphosed sedimentary rock is of 
such uniform composition that the lines of bedding, the original 
lines of deposition, are not easily traced. Along these the rock will 
split more easily than across them. Such lines when too pronounced 
may be a great detriment, not merely as concerns appearances, but 
what is of more importance, as affecting the weathering qualities of 
the stone also. 

Such stone, when used in ashlar -work, are often sawn or split 
parallel with the bedding, since not merely can the work be done in 
this manner at less cost, but a face of more uniform color and texture 
is thus obtained. That the custom is open to serious objection is noted 
in another chairter (p. 93). 

Joints in rocks are matters of interest for still other reasons than 
those noted above, since upon their character and abundance is largely 
dependent the size and shape of blocks that may he extracted. To 
illustrate this point more fully: Plate IV, Fig. 2, shows a quan-y in 
which the rock is traversed by a series of nearly horizontal joints so 
strongly developed that A'ery little labor is necessary to free the sheets 
one from another. Large, flat blocks, with lieautifully fresh and even 
surfaces that can be cut up to any desired size, even to sizes too large 
for transportation, can thus be I'eadily and cheaply obtained. Such 
quarries will furnish blocks for building, for monumental work, for 
monolithic columns or for any purpose to which the rock is lithologi- 
cally fitted. In other cases, where it may be these horizontal, or 
holiom joints, as they are called, are equally well developed, there 
exists a second series of vertical joints running at right angles with 
the first. Such necessarily limit the length or breadth of the blocks 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE IV. 




lie. 1.- IHJIUZONTAL BKDS. 




Fig. 2.-PROMINENT " BKIIDTNT. • .lOI NTS. 



MAEVLANn GEOLOGICAL SURVEY .')" 

()l>t:iiiialilc. 'I'hcsc quarries are best suited for the prodiictioii <jf 
ordinary building and monumental material, and are commonly spoken 
of as bloek quarries in distinction from the sheet quarries alxive noted. 
It is obvious that in either of tin? cases above noted, the joints, 
pro\'ided they are not too near together, and not discolored by sap, 
are of positive benefit to the quarries. It is possible, however, that 
owing to their abundance and to the angle at wliieli they cut each 
other they may be decidedly detrimental or even ruin for architectural 
work what might otherwise be a good quari-v. lu the view shown 
in Plate V, Fig. 1, we have a quarry travei-sed by at least three sets 
of very conspicuous joints cutting each other at sharp and olituse 
angles. The result is that natural blocks, though easily obtained, 
are of limited size and of such in-egular shape that every one must be 
plugged or othenvise squared and dressed down before it is available. 
A quarry thus jointed cannot compete in the production of blocks 
of prescribed size with such as are descrilied above, but can be worked 
economically only for random rublde, or for square blocks where 
so situated as to have particularly favorable facilities in the way nf 
extraction and transportation. 

Effects of AVeatheking and Ekosion. 

All rucks, without exception, when exposed for a sufficient length 
of time to the atmosphere, undergo a process of disintegration and 
decomposition, or weathering, as it is conuuonly called, whereby they 
become converted superficially it mav be into sand, gravel and clay, 
and on the immediate surface into soil. This process of degeneration, 
wliich will be described in detail latei", has been going on throughout 
tlie many thousands of years which ha\e elapsed since the rocks were 
raised above the ocean level, and still continues. Xo portion of the 
land areas have escaped. By its means, accompanied by the erosive 
action of running water and of glacial ice, many hundreds and even 
thousands of feet in vertical thickness of material ha-\e been removed 
from the land areas, and carried seaward. The soil itself is but a 
transitory phase of this weathering process, being continually removed 
above by the water of rains, and renewed below by further decay of 
till' mulerlvinc- rock. Where the ei'osive action of water and of ice 



58 THE BUILDING AND DECORATIVE STONES 

lias not been too excessive, there exists a blanket of varying thickness 
of this rotten material overlying the still sound rock, into which, in 
many a deep cutting, it may be seen to pass by imperceptible grada- 
tions. The fact that all portions of the land are not alike covered 
by this blanket of soil, clay, sand and gravel, is due to the unequal 
erosion mentioned above. At a comparatively recent geological 
period the condition of affairs now existing in Xorthern Greenland 
prevailed all over New England, New York and portions of Pennsyl- 
vania, and a large portion of the Central States north of the Ohio 
and east of the Mississippi River. Huge glacial ice sheets, in some 
cases thousands of feet in thickness, buried the land, and, travelling 
slowly southward and westward, plowed down through this rotten 
material, or dragged and pushed it along, even grinding into the hard 
fresh rock as a workman with file and plane would cut down through 
the discolored and rotten matter on the surface of a piece of tinil)er 
till the sound fresh wood was reached. The result is of more than 
theoretical interest. Throughout the glaciated areas, and particularly 
along the New England Coast the rocks are found to-day hard and 
fresh to the very surface, as shown in Plate V, Fig. 2, necessitating no 
stripping, and scarcely any preliminary work prior to the quarrying of 
merchantable material. The immediate surface, for tlie depth, it 
may be, of but the fraction of an inch, is slightly deadened or dis- 
colored. Below this the stone is strong, clear and durable. In the 
regions beyond the limit of the glacial action, however, the rocks are 
still covered with the mantle of debris, excepting so far as removed 
by water. But as the erosive power of water is so much less than 
that of ice, so here we find the sound stone covered by a mantle of 
from one to many feet of earthy and discolored material which must 
all be removed before actual quarrying operations can commence. 
Even when sound rock is struck it often occurs for a time only in 
bowlder-like masses, omng to the penetration of the decay most 
deeply along pre-existing joint planes. This condition of affairs is 
shown in Plate XIV, Fig. 1. The same condition exists, often in a 
more exaggerated form throughout the Southern States, as in the 
marble regions of Tennessee, and to it is due the prevalent idea that 



MAKYLAND GEOLOGICAL SURVEY 59 

the stone here docs not occur in tnie beds, Init only in " bowlder 
foi-mations." Wiicn apparently fresh stone is found on the immediate 
surface, it is often weakened through a loss of cohesion between its 
particles by the expansion and contraction of ordinary temperatures. 
This is particularly true of the granitic roclcs. 

These facts are dwelt upon here in detail, since they must always 
be taken into consideration in the opening of new quarries. It is 
due to such causes in part that the northern quarriers are enabled to 
compete so successfully in the markets of Wasliington and Baltimore 
witli those nearer at hand. Cheaper transportation by water and 
ready accessibility to shipping points are, however, important factors, 
though the advantages thus gained are in part offset by a more rigorous 
climate, whereby actual quarrying operations must be limited to the 
warmer season of the vear only. 



NICMOI.AS MT .-*"' "'■■ 



755H3^^;t7«;s?jftT • 



Fig. 0. — Section across Western MiirvUuul showiui; restored folds. 

In all this discussion, it is well to remember that the natural sur- 
face of the earth is imdergoing constant change through erosion and 
deposition. EveiT rainfall and iimning stream carries from the higher 
to the lower levels more or less rock detritus, a part of which is even 
transported to the sea, to be permanently lost from the present land 
areas. In short, the surface is being constantly lowered, and deeper 
lying rocks ai'e successively exposed. Just how much the surface 
has been lowered in bringing about the present condition of affairs, it 
is perhaps hard to say. AVhat might at one time have been the land 
surface had no erosion taken place, may be shown in the accompa- 
nying section across western Maryland through AVarrior Kidge and 
Xicholas mountain in Allegany county. In this section the continu- 
ous lines represent, so far as is possible on so small a scale, the present 
land surface, while the dotted lines indicate the portions that have 



00 THE BI'ILDING AND DECORATIVE STONES 

been ercMled away. Where would liave lieen hills ai'e valleys now. 
and in regions Avhcre bnt for erosion wonld have been found nionoto- 
nons stretolies of sand or limestone, each covered by its layer of soil, 
are now accessible by means of their nptnrned edges, beds of a gTeat 
variety of colors, textnre and composition belonging it may lie to 
\\-idely diiferent geological horizons. 

It may be remarked here that the character of the material on the 
immediate surface, is not always a sure indication of that which is t" 
be fonnd beneath. This is due to the variability in weathering quali- 
ties displayed by rocks of different kinds, a matter which is dwelt 
upon in some detail in the following pages. 

Such imperfections as dry seams and joints in rocks are invariably 
more conspicuous in the superficial portion of the quarries, than at 
greater depths simply through the mechanical action of heat an^I 
frost or the decomposing action of water. On the surface such may 
manifest themselves in the form of open cracks, and lines of diseolnr- 
ation, which perhaps wholly disappear or become inconspicuous at 
comparatively slight depths. It must be remembered, however, that 
the absence of these defects does not necessarily carry with it an 
absence of such tendencies as shall cause them to develop under fa\-oi-- 
able conditions. The writer has in mind a quarry in a more northern 
state in which on the immediate surface the stone was to be had 
only in comparatively small, angular blocks owing to the presence of 
innumerable sharp open joints. At a depth of perhaps 20 feet the 
open joints had disappeared, and apparently sound blocks of almost 
any size were obtainable. Careful examination of these blocks, 
however, revealed the presence of sharp, straight lines, as fine as a 
pen scratch, each one of which would correspond to an open joint on 
the surface, but which so long as protected from heat and frost, 
remained quite inconspicuous. It is safe to say that in no case can 
joints, which are conspicuous ag such on the surface, be relied upon to 
disappear entirely at any depth likely to be reached by quarrying 
operations. They are a i^roduct of deep-seated agencies, and extend 
to depths which so far as practical quarrying is concerned might as 
well be without limit. 



MARYLAND OEOLOGICAr, SUEVEV <!! 

The solution, discoloration, and decomposition whicli goes on alono; 
snch juint ]ilanes and line? of weakness may however cease to be 
apprccialile or important at depths comparatively insignificant. Tlio 
ferruginous discoloration, or so called " sap," which is frequently 
found penetrating blocks of stone, particularly of gi'anite, for an inch 
or more along these joints, is due mertdy to the decomposing action 
of percolating water, and below the permanent water level, may quite 
disa]ipear. Once removed from the quarry bed and placed in the 
walls of a building, the conditions are so changed that there is no 
probability of this form of staining making its appearance excepting 
where, it may be, the n)ck carries appreciable quantities of iron sul- 
]ihides (see p. 91). In calcareous ro(d\S, the presence of joints is 
often exaggerated through the solvent action of water, which percolat- 
ing downward carries away the material in solution. Jointed beds 
of marble may therefore, on and near the surface, be reduced to dis- 
connected bowlder-like masses, as is sometimes the case in the marble 
regions of Tennessee. The extent to which such solution has gone on 
is ever variable, sometimes to a depth beyond the limits of practical 
quarrying, and sometimes to but the depth of a few feet below the 
surface. In some cases, even within the limits of Maryland, com- 
paratively thin beds of what was othenvise a most beautiful marble, 
have been so eaten out by this solvent action as to leave only a frac- 
tional part of the original material. Here and there may be found 
outcrops of very promising stone, Init when the beds are traced along 
for very short distances they are found quite obliterated, 'i'o illus- 
trate this point more fully: — The writer was called on not long ago 
for an opinion relative to the probability of an undeveloped quarry 
being able to furnish snflficient material of a certain grade l<> warrant 
the letting of a contract. On examination, there was found in one 
locality, and almost on the immediate surface, a bed some two feet in 
thickness of a beautiful fine white, almost translucent marble. This 
dipped at a low angle beneath the surface soil and to the inexperienced 
observer might, and did seem very promising. On careful inspection, 
however, such an inspection as could be made only by one acquainted 
with the ffeoloaical structure of the countrv and the action of the 



(j3 the building and decorative stones 

atinospliere on rocks of tins class, it was discovered that, on all sides, 
everywhere indeed within reach of practical quarrying operations, 
this Led had become almost entirely dissolved away, leaving only here 
and there small areas too insignificant to be worthy of consideration. 
By exploring along a deep trench that had l)een opened across the 
face of the bed, it was discovered, too, that the lower beds were not 
only quite siliceous and hard but variable in color and often carried 
the deleterious material pyrite. In short, all of the material of any 
value that the quarry could lie relied upon to produce was the small 
amount actually in sight, aggregating at most but a few thousand 
cubic feet. Unfortunately the " practical " quarryman was in this 
case unwilling to accept the conclusions of the geologist and persisted 
in attempting to develop a quarry, only to discover when too late that 
he was wrong and that both his money and his energies had been 
wasted. 

As a general rule the solvent and decomposing action of water goes 
on most rapidly in the softest and weakest portion of the rock, so that 
the residual bo^vldcr-like masses may represent the better quality of 
the material. Excepting then that nature's method is extremely 
wasteful such results can be considered as scarcely detrimental. A 
quarry under such conditions may be actually producing a better, 
more uniform class of material, than one which has escaped solution 
altogether. 

In making search for new localities for opening quarries, it is 
always well to note the manner in which the indi^ddual beds have 
weathered. The soundest and best will as a rule be found standing 
out in relief wliile the more perishable have crumbled away. 

All stone as it lies in the ground contains a certain amount of 
interstitial water, wdiich holds in solution more or less mineral matter. 
This is commonly known as quariy water. When stones are re- 
moved from the quarry bed, this water is drawn to the surface and 
evaporated, leaving its mineral matter to serve as a cement to bind 
the grains together. A superficial induration or hardening thus takes 
place. This phenomenon has been long since recognized by quarry- 
men, though the cause of the same has not been generally known. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE V. 










s 




\ 



' "T: ff^ li'-' 







I'ic.].— UUAHliY S1I()\\'I\(; Sl:\Eli.\L SEIUKS Ol-' .IIIIXTS. 




Fii;. •J.-GLACIAL STHllM'KU QCAUUY. 



MARYLAND GKOLOGICAL SfRVKV 03 

That a stone is soft when first quarried ami hardens on exposure, is 
one of the commonest araiinients nsed hv qiiarriers with reference to 
their material, though they fail to remember that such induration may 
be temporary, and the rock in time cnimble in spite of it. Sand- 
stones are f>eculiarly liable to such induration, even in exposed o\it- 
erops in the quarr\- bed, so that casual inspection will give quite erro- 
neous ideas as to the actual quality of the stone. A slight change 
in color, from the surface downward, is also a not infrequent occur- 
rence, as is noted in the chapter on Weathering (p. 90). 

Color of Rocks. 

The subject of the color of a rock, when fii-st quarried, after iiro- 
longed exposure, aud after working is one that should be brietly con- 
sidered. Among siliceous crystalline rocks the colors are due mainly 
to the presence of colored minerals, or to the physical condition of the 
feldspars. Tlius the gray color of granites is due largely to an 
admixture of white feldspars imd ])laek mica or hornblende; the red 
colors to red feldspars; the dark greenish, sometimes almost l>lack 
colors to clear pellucid feldsp.nrs. and the white, to white feldspiirs. 
The dark colors of the diabases aud the gabbros are due to the pellucid 
feldspars and the dark pyroxenes they carry. Pure limestones and 
dolomites are white simply because that is the color of tlie calcite or 
dolomite which forms their chief con.stituent. The dark color com- 
mon in this class of rocks is due as a rule to the presence of carbcm- 
aceous matter: the red. to iron oxides, though the pink and red colors 
of some of the onyx marbles seem to be due in part also to organic 
matter. The red, brown and yellow- colors of sandstones are due to 
iron oxides. The changes in color which these rocks are likely to 
undergo, on exposure, are noted in the remarks on rock-weathering. 
It may not be out of place to state here, however, that nearly any 
feldspathie rock is likely to become lighter in color during the incip- 
ient stages of weathering owing to the. opening up of the cleavage 
l)l:incs in the feldspars. It is for this same reason that the hammered 
surface of one of these rocks is of a lighter color than the natural rock 
face or polished surface. The impact of the hammer breaks up the 
graniiles on the immediate surface so that the light falling upon it 



04 THE BUILDING AND DECOJtATIVE STONES 

is reflected, instead of absorbed, and the resultant effect npon the 
eye is that of whiteness. The darker color of a polished surface is 
due mei'ely to the fact that through careful grinding all these 
iiTegularities and reflecting surfaces are removed, the light pene- 
trating the stone is absorbed, and the effect upon the eye is that of 
a more or less complete absence of light or darkness. Obvioiisly then 
the more transparent the feldspars and the greater the abundance of 
(lark minerals, the greater will be the contrast between hammered and 
polished surfaces. This is a matter worthy of consideration in cases 
where it is wished, as in a monument, to have a polished die, sur- 
rounded by a margin of hammered work to give contrast. Often when 
a piece of work of this nature is exposed, the contrast between ham- 
mered and polished work diminishes slightly owing to the gradual 
weathering out of the particles splintered through hammering. The 
contrast is less when the stone is wet than when dry, because the water 
fills all the little rifts and crevices and by its refracting power tends to 
produce tlie same effect as though the stone were polished. 

Geological Age. 

The matter of geological age is only of very general economic inter- 
est. It is indeed true that the process of metamorphism — the change 
from the amorphous or fragmental condition to one more or less crys- 
talline — has as a riile gone on more extensively among the older 
rocks, than among those later formed, but the rule is by no means 
universal, and moreover metamorphism is not always productive of 
such characteristics as make a stone adapted for either building, monu- 
mentnl or decorative work. "While metamorphism may render a 
stone crystalline, it may also render it granular and friable; while 
it may develop color, it may also develop schistosity and other blem- 
ishes. So far as the United States are concerned, one can say, how- 
ever, that few stones are used to any extent that are of later date 
than the Triassic, and that few if any of our marbles are younger than 
Silurian, wliilc nearly all our granites, as now quarried, belong at 
least to Paleozoic or Archaean times. Stones of later than Triassic 
age, are, so far as relates to the Eastern United States so friable, or 
so poor in color, as to be of little value. 



mauvi.and geological survey 65 

The Strength of Stones. 

]\riicli lias ill times past been written on the subject of rlie erushing 
strength of building stones, and hundreds of tests have been made, 
the results of a few of which are given in this work. A few words 
only on the subject are here necessary. It is doubtful if in any but 
the most extreme cases it is necessary to continue this line of inves- 
tigation. The results thus far obtained are sufficient for us to for- 
mulate general rules, and the average results obtained are so vastly 
in excess of all ordinary r("i|iiirements that they may safely be ignored. 
A stone so weak as to be likely to crush in the walls of a building, or 
even in a window stool, caj) or pillar, bears so visible marks of its 
unfitness as to deceive no one with more than an extremely rudimen- 
tary knowledge on the subject. It is rare to find a stone that %vill 
not slidw, under the methods of testing now in vogue, a cnishing 
strength of at least 6000 lbs. to the square inch, while many stones, 
particularly those of the granite group, will range as high as 20,000 to 
30,000 lbs. to the square inch. Since the first named amount is ten- 
fdld mure than is likely to be re(|uircd of it in any l)ut the most 
extreme cases, the absurdity of making further tests is manifest. 
The few that have he're been made, were made in recognition of the 
still prevailiTig — though mistaken — demand for tests of this nature. 
They show, as was to be ex|)ected, that the matter of the strength 
of those of the ^[aryland stones now on the market, may well be left 
out of consideration in the future, .and this for the reasons above 
suggested. 

In fact, it is the weathering (piality of a stone more than its ulti- 
mate strength, tiiat should concern ns, and a careful examination of 
the natural outcrops, old (piarry faces and buildings, will give a 
more correct idea to an experienced man, than will all the tests that 
can be made in the laboratory. This view the writer expressed some 
years ag<i,' and to it he still adhci-cs with little fear of contradiction. 

CiEOGRAi-nic DisTRii'.iTiox OK Stoxe in the State. 

r>v ri'ferring to the ma]! of Maryland (Plate VI, Vol. I), it will be 
seen that the state is dixided into ihi'ee well defined topographic ])rov- 

' Stoiu's for liiiildint;' :iiul Decoration, Wiley and Sons, .\. Y. 
5 



66 THE BUILDING AND DECORATIVE STONES 

inces, which are intimately related to its geologic structure and 
hence have a bearing upon its mineral yielding capability. It will 
therefore be worth our while to devote a little space to a consideration 
of this branch of the subject, bearing in mind, the while, that much 
that is said here regarding Maryland is true to a certain extent of the 
entire Eastern United States. 

The most easterly of these topographic provinces, kiio-\vii as the 
Coastal Plain, comprises the area between the Atlantic Ocean and a 
line passing X. E. to S. W. from Wilmington (Delaware) to Wash- 
ington, D. C, through Baltimore. The region is about 100 miles 
broad in its widest part, and includes very nearly 5000 square miles 
of territory or about one-half the area of the entire state. It is 
characterized by broad level-topped stretches of countiw, which ex- 
tend with gradually increasing elevations, from the Coastal border, 
where the land is scarcely at all elevated above sea-leA^el, to its Avestern 
edge, where heights of 500 feet and more are to be found. Tlie 
underl\-ing rocks are as a rule but slightly indurated, consisting mainly 
of clays and sands, sometimes locally cemented into ferruginous sand- 
stones and conglomerates and never of such consistency as to be of 
value in their natural state for building purposes. We may therefore 
dismiss this portion of the state fiMui further consideration. 

The second province, known as the Piedmont Plateaii, borders the 
Coastal Plain on the west and extends to the base of the Catoctin 
]\Iountain. It is nearly 40 miles in .vidth in the southern portion of 
the region, but broadens towai'd the north until it reaches 65 miles in 
width, comprising altogether an area of approximately 2500 square 
miles, and including Cecil, Harford, Baltimore, Howard, Montgom- 
ery, Carroll and Frederick counties. As it is this proA-ince which 
furnishes by far the larger amount and greater ^-ariety of building 
stones and marliles, it will be worth the while to consider it in some 
detail. The Plateau, as a whole, is divided very nearly in its central 
portion by an area of high land known as Parr's Eidge, into an eastern 
and a western district. To the east of this ridge lie the gneisses, 
granites, galibro.s, ciwstalline dolomites (marbles), serpentines, and 
roofing slates, the main portion of the area being occupied by the 



MARYLAND GEOLOOICAL SURVEY 6T 

gneisses, througli whieli have boon sporadically iiitnulcd the granites 
and iialiliros wliicli, by erosion, are now exposed in tlie form of isolated 
patclies of comiiarativcly limited extent, as shown on the map. The 
building marbles of the state arc limited almost wholly to this eastern 
division, as shown in the areas north of the city of Baltimore. 

This eastern division has, on account of its crystalline rocks and 
their complicated structure, a diversified to])ojira])liy. Along the 
eastern ni;iri;in the land attains, at several ])oints. heights exceeding 
400 feet, reaching at Catonsville 525 feet above sea-level. To the 
west the conntry gradnally increases in elevation nntil it culminates 
in Parr's Kidae, which exceeds S50 feet in Carroll connty. 

'I'lie drainage of the eastern district is to the east and southeast. 
On its northern and southern boundaries it is traversed by the Sus- 
quehanna and Potomac rivers, which have their sotirces without the 
area, while the smaller streams, which lie betweeti them either drain 
directly to the Chesapeake Bay or into the two main rivers. Among 
tli(> larger of the intermediate sti'canis are the Patuxent, Patapsco and 
(Tunpowder rivers, whose headwaters are situated upon Parr's Ridge. 
The Patapsco especially flows in a deep rocky gorge nntil it reaches 
the Relay, where it debouches into the Coastal Plain. All these 
streams have ra]iid currents as far as the eastern border of the Pied- 
mont Plateau, and even in th(> case of the largest rivers are not navi- 
gable. 

This last is an important item since it precludes the possibility of 
shipment of (piarrird material by other than rail, canal or wagon 
routes. 

The western division extends from Parr's Ridge to Catoctin ^Nfotm- 
tain. Along its western side is the broad limestone valley in which 
Frederick is situated, and through wliich flows the llonoeacy River 
from north to sontli, entering the Potomac River at the boundary line 
between ]\[outgomerv and Fn'derick counties. The valley near Fred- 
erick has an elevation of :io0 feet above tide, which changes slowly to 
the eastward toward Parr's Ridge, and very rapidly to the westward 
toward Catoctin ^lountain. Situated on the eastern side of the 
valley, just above the mouth of the Monocacy River, and breaking 



68 THE BUILDING AND DECORATIVE STONES 

the regularity of this surface outline, is Sugar Loaf ilountaiii, which 
rises rapidly to a height of 1250 feet. 

The underlying rocks of this division are as a rule far less crystalline 
than those of the eastern, consisting mainly of blue gray limestone, 
red brown sandstones, phyllites, and other siliceous and argillaceous 
rocks which are largely unsuited for construction purposes and hence 
need no mention here. There are, however, in Carroll and Frederick 
counties several comparatively small included areas of highly crystal- 
line limestones capable of furnishing in small blocks material of such 
color and texture as to make them of value as marbles. 

The third or Appalachian region borders on the Piedmont Plateau 
and fiirms the entire western portitjn of the state. It includes the 
western portion of Frederick, and all of Allegany and Garrett coun- 
ties, an area of some 2000 square miles. This is the most mountain- 
ous region of the state, consisting indeed of little more than a series 
of parallel mountain ranges with deep narrow intervening valleys 
which at the southern limit of the state are cut almost at right angles 
by the Potomac River. This area has as yet furnished practically 
nothing in the way of structural material though it does not neces- 
sai'ily follow that satisfactory materials do not exist. The rocks con- 
sist mainly of .sandstones, shales and limestones, none of the latter 
being sufficiently metamorphosed to make them of value as marbles. 
The possible resources of this region will be discussed later. 

Methods of QuAREviNa and Woekinc;. 

In the work of extracting stone from the quarry, and reducing it 
to the desired shapes for use, there are two considerations of primary 
importance. These are, 1st, the accomplishing of the work with 
the least possible injury to the material, and, 2nd, the accomplishing 
of it cheaply. I'nfortunately the two methods are almost directly 
opposed to each other, and equally unfortunately the cheaper methods 
are those, as a rule, most likely to produce injurious results. This 
last is only partially true, however, since where the work is carried on 
on a large scale, the better way proves in the end the cheapest. In 
many kinds of manufacture complaint is made that machine-made 
goods are inferior to those made by the old-time hand processes. In 



lfARrr.AXD GEOLOGICAL SrRVEY 69 

stone work tins is coi-tainly not correct, liowcvcr. AVilli iiiacliiiics it 
is possible to produce better results, in less time than by liaml meth- 
ods. This is particnlarly tnie rcgai-ding quari-ving, sawing, grinding 
and poiisliing. There are of course certain kinds of work, certain 
forms of finish, for the satisfactory performance of which no machines 
have been designed. 

[before considering in detail the methods employed in stone (piarrv- 
ing and stone working, let ns first consider the conditions under wliich 
the stone exists in the quarry, what difficulties are to be overcome, 
wliat methods can be ])nrsuc(l with safety, and what must 1)(' avoided. 
All stone that is used at all extensively for structural purposes has the 
property of splitting, or breaking with fairly flat and even faces, 
along two directions at right angles to each other. The direction 
of greatest ease is known as the rift, that at right angles as the grain. 
The cause of this tcndcuey to split .nloug definite lines is not fully 
tmderstood. It is enough for our present purposes that it exists. 
The rift is often very ])ronounced, and its direction is indicated by 
and some is due to a parallel arrangement of the constituent minerals 
as in the gneisses and schists. In other rocks, like the more massive 
granites, it is wholly inconspicuous and the direction can be deter- 
mined only by an experienced stone-worker. Xothing is more sur- 
prising to one who has given no attention to the subject, than the ease 
with which a workman, with no other tool than a scpiare-faced hammer 
will break out by a few well directed blows a rectangidar block of 
the required size and shape for street pavements, while an inexper- 
ienced person, with the expenditui'e of twice the amount of time and 
triple the amount of energy will produce only a shapeless mass, with 
bulging faces and rounded connn's, utterly worthless and unfit for use. 
Here then are two important factors which must be taken into con- 
sideration. Another is the jointing. To this property attention has 
been called on p. 55, and the matter need not be wholly repeated here. 
It shonld be stated, however, that these joints may b(> either a help 
or hindrance to quarrying according to their prominence, abundance, 
and the directions at which they traverse the stone. As a very gen- 
eral rule those massive rocks which are extcTisively quarried owe their 



70 THE BUILDING AND DECORATIVE STONES 

availability to the presence of two series of joints which like the rift 
and grain cut the stone in directions pi'actically at right angles with 
each other. This condition of affairs is described on p. 50, and a 
figure is given shomng the utility of joints in quarrying. Hence 
nothing more need be said on the subject here. 

Among sedimentary rocks — the sandstones and limestones — the 
better grades of stone lie in well defined beds, or layers, separated 
from one another by other beds of inferior or worthless material. The 
quarrier has to consider not only how to get out the good material, 
but also how to get rid of that which is worthless. One method must 
be resorted to for the first, and another less expensive for the second. 

Another feature which must not be lost sight of, here, is the 
difference in degree of hardness and toughness of A-arious classes of 
rocks. A method of treatment allowable in one case, as with granites, 
woidd be wholly impracticable in another, as with limestones. For- 
tunately those rocks which are sp tender as to be likely to become 
injured by the more violent methods of quarrying, as by blasting, are 
sufficiently soft to permit of their extraction by other means. The 
quarrier has to remember that stones have but a comparatively small 
amount of elasticity, that thev are brittle, and any sudden jar, like 
that from an explosion of powder or dynamite, is likely to develop 
fla-ws and fractures, which, while they may be quite inappreciable at 
first, become injuriously conspicuous by weathering. 

But enough has been said to show that quarrying is not quite so 
simple a process as may have at first appeared. Let us now devote a 
few pages to a consideration of the methods in vogue. 

The old time and simplest method of quarrying which needs be 
considered here, is that of blasting out the rock by means of powder 
exploded in a cavity made by hand drills. This method, aside from 
being too slow for modern purposes, results in the production of only 
irregularly shaped blocks requiring a proportionately large amount 
of labor to rediice them to the desired sizes and shape. Moreover, the 
explosion of a single, large charge of powder, is likely to produce a 
shattering which can be wholly done away with if the charge is dis- 
tributed along a line among several holes which are exploded simul- 



MAKYLAXD GKOLOGICAL SUKVEY 



71 



taneoiislv. This nu'thod is rendered possible through the invention 
of a steam drill sneh as is shinvn in Fig. 7. As may be seen it 
consists of little more than a steam cylinder mounted on a tripod with 




Fig. 7. — lugersoU-Sergeant steam drill. 



the drill attached to the piston. The machine is held in place by 
means of heavy weights on the legs of the tripod. The steam being 



(3 THE BUILDING AND DECOBATIVE STONES 

conveyed from the boiler to llie drill by means of a ilcxil)le hose, 
which allows the use of the drill in any part of the (jiiariy. A differ- 
ent form of drill answering the same purpose is shown in Fig. S. By 
means of these machines a series of two or more holes are drilled along 
the line where it is desired the stone shall break. These are then 
charged lightly with powder, and fired simultaneously by means of 
electricity instead of by a fuse. The result is that a large mass of 
rock is freed from the quarry bed, with a comparatively slight amcnint 




Fio 



-lugersoll-Sergeaut quarry bar drill. 



of jar, the aim of the quarrier always being not to move the block 
any appreciable distance, but simply to free it, after which it is re- 
duced to blocks of the required size by hand implements, to be noted 
later. Where the bottom joints in a quaiTy are well defined as at 
Vinal Haven, Maine, masses of granite some 300 feet in length and 
20 feet in width liave been loosened at a single Ijlast.' In cases where 
bottom joints are not sufficiently developed, or are at too great a dis- 

' Stones for Building and Decoration, 3nd Ed., p. 241. 



.MAKYI.AM) liKOLOGICM. SIRVKV 



73 



tance apart, it is soiiietiiucs necessary to resmt In drilling and blasting 
to free the rock from the quarry bed. 

Once loosened fnnii the bed, as described abnve, a blcjck of granite 
or other hard rock, is ent u]) into (l(>sii-eil sizes by means of ])lngs and 
feathers. liy means of hand drills or a quarry bar drill, a series of 




Fic. '1. — Warchvell oliaiiuellimr machine. 



IidIcs, niit over an inch in diaiiK'ter and a few inches deep, is drilled 
along the line where it is desired the stone shall break. Into each 
of these is then placed two half round wedge-shaped pieces of soft 
iron, the thicker ends downward, and between them is inserted a small 
steel wedge. When the wedges or plugs are all in place tiie workman 



74 



THE BUILDING AND DECORATIVE STONES 



n 



strikes them one after the other with his haiumer, driving- them all 
alike, thus produeing a uniform strain along the line, until the 
block falls apart. The method is commonly known as " plug and 
feather " splitting. In the softer rocks, as the sandstones, a somewhat 
diiferent metliod is resorted to. Instead of drill holes, grooves are 
first cut with picks, and into the gTooves large steel wedges are 




i-Hi. 10. — luLiorseill-SeliiX-ant chauiielliiiu" liiachilif. 



inserted which are then driven with heavv striking hammers or 
sledges, in the same manner as before. 

Blasting by means of powder furnishes the only aA'uilahle means 
for quarrying rocks of the granitic type, owing to their hardness. 
But the method should be used reasonalily and with discretion. 
Material from a quarry where, as one sometimes reads, hundreds or 
even thousands of tons of stone have been loosened by a single blast, 



JIARYLAXD GEOLOGICAI, SfKVEY 



75 



should always be accepted with hesitation, if at all, for building pur- 
poses, since as above noted the jar from such a couccutrated explo- 
sion is likely to produce incipient fracture and injuriously (hnejo]) 
latent joints. 




Fig. 11. — Kcvolvins drum and hoist for derrick. 
(Forntshed by American Hoist and Derrick Co.. St. Paul. Minn.) 



In quarrying softer 'rocks like the sandstones, limestones and mar- 
bles, channelling machines are now used in nearly all American quar- 
ries. Two distinct types of these machines are used (Figs. 9 and 10), 



76 



THE BUILDING AXD DECORATIVE STONES 



but with both the results are essentially the same. The machines are 
constructed to run forward and backward over temporary tracks laid 
on the quarry floor and to cut as they go straight smooth channels 
into the stone beneath, the channels, l)y repeated passage of the ma- 
chine, being cut to any desired depth up to perhaps six or more feet. 
The rock on the floor of the quarry is thus divided up into a series of 




Fui. V: 



-Lincoln stone jilaner. 



blocks which need only to be freed from the quarry bed to become 
available. This freeing from the bed is usually done by means of 
machines known as undercutting or " gadding " machines. These 
are sometimes ordinary impact steam drills, or again diamond drills. 
In either ease a series of holes is drilled along the desired line, and 
the stone then broken out by wedges, or perhaps by means of another 
machine wliicli simply cuts out the partitions between the holes. 



MARYLAND GEOLOGICAL SIK\EY II 

V>y tlic niil iif pucli inachinps blocks of any dpsirerl size may be ob- 
tained, and what i-< of ('(pial inijiortance, scloctcd uuitorial can he 
taken (Hit wiili n<i i>iissil)le daiiii'cr of injury as hv lilastini;'. 

The renioxal of Kiocks fmni tlic iiiiarry to the slied is accimiplishod 
liy iioists using hoi'sc, steam or clectric-ity fin' powi'r, the rnnninii- 
licar passinji' over tiie arm of a ih-rriek as in Plates X and XIV, or 
through a truck on a cable as in Plate XXXTT. Tiie cable permits the 
lifting of blocks from any portion <il' the ipiarry along the line of 
the main cable, tlie deri'icdc liandliiiL;' all of the material within a given 
distance of its base. The time and expense involved in pulling around 
the arm of the derriidv by a rope may be lessened by the use of small 
drums connecting with a horizontal wheel as shown in the acci)m])any- 
ing figure (II) or in less detail In the [ihotograph id' the i'ort Deposit 
quarries (]>. 144). 

Once removed from the i|iiarries stones are cut and tinislied by 
processes, which within certain limits vary aecordini; to I he hard- 
ness of the material, ihongh I he nature of the rift or liedding mit- 
nrallv has much to tlo in the matter, (iranites and hard rocks 
of this nature are as a ruli' reduced to the desired size and shape 
by idug and feather splitting and by hand cutting with chisel and 
hammer. Steam saws eonsisting of a thin blade of soft irou fed 
with small globules of ehilled iron or a sand com])osed of crtished 
steel are used to some extent. .Monolithic cohnnns are in some 
instances turned on giant lathes, the cutting tools being revolving 
discs of steel. A ])laner with cutting discs of the same nature 
is sometimes used (see Fig. 12). Smooth surfaces for ]iolishing 
are ]iroduced by grinding, the bloidc being placed on a horizontally 
re\-iihing iron bed, the cutting material being the chilled iron, 
sand or i mery as the case may li(>; or, where the block is too large 
there is used a movable grinder such as is shown in !• ig. b!. The 
necessary smooth surface lia\ing been produced, the ]iolish is im- 
parted by means of a revolving wdieel covered with felt. 1'his is 
kept wet and a white powder, known to the trade as " iiolishing 
putty" is sprinkled over the surface occasionally, the friction from 
the revolving wheel aided by the putty shortly in-oducing the desired 



78 



THE BUILDING AND DECORATIVE STONES 



results. All almost perfect surface is the first essential to the pro- 
duction of a good polish. Sandstones, limestones and marbles are 
sawn by the reciprocating blades of soft iron mentioned aliove, which 
are usually mounted several or many in a frame, an inch or more 




Fig 13. — Stone pulisher. 



aj)art according to the thickness of the slabs or blocks which are to 
be cut, the cutting material as before being sand or chilled iron. 
Sand is preferable Avhen the material to be cut is not too hard, since 
not likely to stain the stone, through nisting. Moreover little parti- 
cles of the iron or steel are likely to become imbedded in the stone 



MARYLAND fiEOl.OGlCAL SURVEY Tl) 

(luring the early stages of grinding and these breaking loose during 
the later stages, when the surface is nearly smooth, do much damage 
by scratching or else remain pernuniently imbedded to give rise to 
rust spots wlien the stone is exposed to moisture. These softer stones 
are also planed by machines operating on the same principles as those 
used in jjlaning metals. A modification of the same machine is used 
in producing moulding'^. Caived surfaces ar(> still ]iroduced mainly 
by band, banmicr and chiscb thuugli machines operating like minia- 
ture stream drills have been enipbiyed for this purjiose. 

N'arinus fcu'ms of finish are applied to the sin-facos of stones, and arc 
called by names as a rule indi<-ativ(' of the means employed. A rock 
fa( (• t!iiisli is till' natural fracture uf the rock, scarcely touclic<l ly 
chisel. A pointed face is a rock face the inequalities of which have 
been reduced by a sharp pointed implement known as a point. A 
surface cut into parallel shallow grooves from a (|uarrcr to a half-inch 
in diameter, is known as a dove-surface. A tiidth-chiseled stirface is 
produced by means of a wide chisel, the cuUing edge of which is 
toothed like a saw. Ax oi' pean hammered surfaces are produced by 
striking upon the surface, always in one direction, with heavy ham- 
mers, the cutting faces of which are reduced to an axdike edge, the 
result being that the finished surface is covered with long parallel- 
lying lines and ridges. A patent hammer made up of thin plates of 
steel so bound together as to form a compound cutting edge is also 
used for tliis work. 

If is Well to call attention here vo the fact that in material so 
inelastic as stone the resvdt of the impact of such blows, however 
slight, on the siirface, is to produce jninute fractures parallel to the 
surface, which result in scaling. The scales thus loosened are, it 
may be. but slight and at tirst inconspicuous. Nevertheless the tenac- 
ity of the stone for a variable distance below the surface has been 
weakened, and here disintegration must first make itself appai'ent. 
Eeyoiul doubt the most durable finish is a rockface, sawn or properly 
lircjiared polislu-d surface, since in th''s(< the natural condition of the 
constituent minerals or granules remains undisturbed. 

It niav bo stated here that all stone works more easilv when newlv 



80 THE BUILDING AXD DECORATIVE STONES 

quarried tlian after seasoning, though this characteristic is more 
strongly marked in the sandstones and limestones than elsewhere. 

iSFot only do stones harden through seasoning, but the rift anil grain 
are often less pronounced, and dry seams and other defects become 
more pronounced. Hence it is always best to work up stone as soon 
after its removal from the (juaiTv as possible. Indeed roofing slate, 
as every quarrier knows, cannot be split at all satisfactorily after the 
water has once dried out of it. 

Relation of Maryland to other Producing Areas. 

The same geological agencies which were instrumental in the 
forming and rendering accessible of so large a variety of stone in 
ilaryland operated throughout almost the entire Eastern United 
States and were productive of A'ery similar results. From ISTorthern 
K^ew England to Central Georgia, along the entire length and breadth 
of the Aii])alnrliian chain, conditions of sedimentation and uplift, of 
eruiition and metamorphism were so similar, that a remarkable uni- 
formity exists so far as regard to character of materials is concerned, 
though in quantity, accessibility and quality, there is often a very 
great diversity. It will be of interest as well as not unprofitalile for 
us to devote some space to a consideration of the resources of the 
neighboring states, and to the conditions governing their output, 
since here, as in other l)usiness enterprises, competition is likely to play 
an inqwirtaiit part in all ntlicr llian ])urely local markets. 

PRELIiriNARY GENERALITIES. 

The axis of disturbance, above repeatedly referred to, extends from 
Maine southeasterly, not parallel with the coast, but retreating grad- 
ually inward, until south of Xew Yurk it is no longer accessible by 
tide-water (■(imnuniicatidn. This is an ini|i<irtaut }ihysiographic feat- 
ure, since transportation by water is always cheaper than by rail. 
This is particularly the case with heavy and indestructible materials 
like stone. In ]\Iaine many of the quarries are either directly upon 
the coast or borderino' alonji' its numerous tiurds and rivers. The 



JfARVLAND GEOLOGICAL SURVEY 81 

qiian-iril iiiatorials, witli scarcely any prcliiiiiiiarv liandlino', can be 
placed directh' upon schooners and carried to all the leading cities of 
tlie eastern United States without transshipment. Hence Maine and 
Massachusetts granites and Connecticut sandstones early came into 
use thronghoiit the entire coastal area of the eastern United States and 
in some cases were even carried ardnnd Cape Horn to cities upon 
the western coast (Plate V, Fig. -2). l''urther than this Xature has, 
througliont the entire Xew England states and large portions of New 
York and Pennsylvania, greatly favored qiiarrving operations through 
the niciliinii iif the ghu-ial ice sheet. This jiuwcrrnl crnsive agent 
carried oil' the residuary j)roducts which result from years of rock 
decay and left the ledges of granite, slate, marble, or whatever they 
may ha\-e been, fresh and hard to the ^-ery surface. Throughoxit the 
entire region to the south of the extension of this sheet, it is only 
here and there TJiaf there is td be found a quarry not buried liy rotten 
matter that must be removed by stripi>iug before quarrying can be 
commenced. This latter fact is well kuown to Maryland quarricrs, 
and is shown iu the views of quarries given on Plates XVIII and XX. 

KINDS OF STO.NE rKODUCED HY OTUKK STATES. 

In Maine there are in operation to-day only quarries of granite, 
gneiss and gabbro, and of roofing slate. Very many of the granite 
quarries lie so near the water's edge that cost of transpoi-tation is 
reduced to the mininum, and hence qiuirriers are enabled to compete 
with others, even iu markets at a great distance. The roofing slates 
lie remote from Avatcr ways and only the general excellence of the 
materials enables them to compete with othere beyond the state limit. 
The output of these materials for ISS!) was: of granite 0,701,340 
cubic feet valued at $2,225,839.00, and of slate 41,000 squares, 
valued at $201,.^(i(i.()0. 

Neiv Ilinnpshire has only quarries of granite and gnei.-is that need 

be here considered. These are all dependent upon railroads for 

transportation, but the quality of some of the granites, notably those 

of Concord, enables them to compete successfully with others more 

G 



82 THE BUILDING AND DECORATIVE STONES 

favorably situated. The entire ovitput for the year 1S89 was 2,822,- 
026 cubic feet, valued at $727,531.00. 

Vermont produces a greater variety of materials than either of the 
above mentioned states, including granites, marbles and roofing slates, 
although few of the granites are of such a nature as to lead to their 
being transported beyond the state limits, so long as the transporta- 
tion is limited wholly to railways. The mai-bles and roofing slates 
are, however, of siicli quality as to lead to tlieir use, even imdcr these 
adverse conditions, in nearly every state in the Union. 

During 1889 the statistics of production of the three classes of 
stone mentioned above were as below: granite (and allied nicks) 
1,073,936 cubic feet, valued at $581,870.00; marbles 1,068,305 cubic 
feet, valued at $2,169,560.00; roofing slates 236,350 squares, valued 
at $596,997.00. 

The marble of Vermont, it should be stated, is, with the exception 
of the colored varieties of Mallett's Bay, almost wholly crystalline 
limestone and of such a nature as to make it better adapted for monu- 
mental and decorating work than general building, while those of 
[Maryland are dolomites, and, so far as now developed, almost wholly 
building marbles. 

Massachusetts. This state produces for other than local uses only 
granites, marbles and sandstones. With the exception of the granites 
which lie along the coast, as those of Gloucester, Eockport and 
Quincy, the transportation is wholly by rail. ISTevertheless the qual- 
ity of the stone, the early date at which the quarries were opened, and 
the energy of the operators has been such that they have been 
widely iised, and in many cases to the entire exclusion of equally good 
material from close at hand. The jnarbles are crystalline granular 
dolomites and wholly of the building type, and on casual inspection 
are scarcely to be distinguished from those of Cockeysville, J\laryland. 
Sandstones are produced only in tlie southern central part of the state, 
as near East Long Meadows, the stone bearing a general resemblance 
to that of Seneca Creek in Maryland, though perhaps of a warmer 
hue. Many of the granites, as those oi Quincy, Dedham and Milford, 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXVII. 




RED SANDSTONE. 

SENECA, MONTGOMERY COUNTY. 



jrAKVI.AXD GKOLOGICAI- SUBVEY S3 

are of a tv|)e quite lackinsi' in other states. Tlic output of the three 
classes durino: 1889 was as below, no statistics for inai'blc being avail- 
able: granite 9,587.996 enbic feet, valued at $2,503,503.00; and 
sandstone 1.907,179 cubic feet, valued at $649,097.00. 

Bhode Island. Only the granites of this state need consideration 
from our present standpoint. Xear Westerly are quarries of a fine, 
evenly textured stone of gray or sometimes pink color, that has 
come to be extensively utilized for monumental work in all our cities 
and towns. The transportation is both by rail and water. Westerly 
being at the extreme western border of the state, with direct rail 
communication to New York and Boston and but a few miles from 
Long; Island Sound. The outptit of granite for tlie entire state for 
1889 was 2,878,239 cubic feet, valued at $931,216.00. 

Connecticut like Massachusetts produces granites, marbles and sand- 
stones. The marbles like those of Massachusetts are white, crystalline 
granular, in part dolomites and in part limestones. The granites, 
with the exception of some coarsely variegated gneissoid rocks occur- 
ring at Stony ( 'r(!<>k, are little used outside of the state. The sand- 
stones, and especially those along the Connecticut River, as at Port- 
land and Cromwell, are very extensively qiiarried and owing to the 
ready transportation facilities offered by the river, arc cxtensi^'ely util- 
ized in all the Eastern cities, and have even been sent around Cape 
Ilorii to San Francisco. These sandstones are brown Triassic stones 
of the same type as those of Seneca Creek and other points in Fred- 
erick county, Maryland, and it is only that they so lie as to offer 
exceptionally favorable facilities for quarrying and transshipment that 
the Man-land st(nie has not thus far jiroven a more successful com- 
petitor. The statistics for the state for 1889 so far as available are 
as follows: granite 3,835,704 cubic feet, valued at $1,061,202.00, and 
sandstone 2,821,430 cubic feet, valued at $120,061.00. 

Neiv York: This state, like Pennsylvania, yet to be noted, is so 
situated with reference to the Appalachian system, and comprises so 
large an area, that its resources are great and varied. Within its 



&■ 



84 THE BUILDING AND DECOKATIVE STONES 

liorders are to lu- found f|uaiTics of iiTaiiite and allied rocks, marbles, 
sandstones, quartzites and slate. The p-anites, of both red and 
gray colors, are eminently suited for building, decorative or monu- 
mental purposes. The quarries are, however, largely in the northern 
central part of the state and i-emote from waterways, so that the 
stones are little used for general building outside of the state. Dolo- 
mitic marbles, coarsely or granular crystalline in structure and util- 
ized only for general building, occur in the southeastern counties of 
the state. Those ('(unjiare clusely with those of ( 'ockeysville in Mary- 
land, and will compete with them on about even terras. In St. 
Lawrence county are other coarsely crystalline, gray building marbles, 
which are, however, little used lieyond the state limits. Black, gray 
and variegated marliles suita]")le fur interior decoration occur in the 
northei'n and eastern j)art of the state, but being of a type wholly 
distinct from any known to exist within the limits of Maryland, may 
for the present he omitted from consideration. Sandstones and quart- 
zites, suited for building and flagging, occur in inexhaustible quan- 
tities widely distriliuted throughout almost the entire length and 
breadth of the state, some of the better known being the Potsdam 
quai-tzites of St. Lawrence county, the Medina sandstones of Monroe, 
^Niagara and intermediate counties and the so-called " bluestone " or 
"flagstone" of Albany, Green and Ulster counties. The Potsdam 
stones are accessible by rail, and the water routes of the Great Lakes; 
the Medina, also, while the flagstones last named are largely within 
comparatively easy reach of the Hudson Eiver. Hence all these 
.stones are widely and for the most part favorably known. The slate 
producing areas are limited wholly to the extreme eastern portion of 
the state, Washington county alone being a constant producer. The 
material is of red or green color, and on this accoimt does not enter 
into direct competition with that of Maryland. 

The quarry statistics (if the state for 1S89 are as below: 

Granite 1,515,511 cu. ft. valued at $ 222,773.00 

Marble 1,171,500 cu. ft. 354,197.00 

Sandstone f;,490,406 cu. ft. 1,177,822.00 

Slate l(i,7()7 squares 81,726.00 



MAini.A.vr) nKoi.ooTrAL sruvEv 8» 

Xeic Jersey. This state produces only brown Triassic sandstones, 
similar tn those of Frederick and ^Montiioinery counties in ifarvland. 
wliicli need consideration here. Tlie close proximity of the state 
to the leadin": markets, as of those of Xew York, Piiiiadelphia, Balti- 
more and "Wasliiiigton renders it possible to transport the quarry 
l)roduct at comparatively low rates, even though such transportation ' 
must be made mainly by rail. The Triassic belt extends from the 
Xew York state line southwesterly to the Delaware Eivcr. 'I'he 
]iriuci|in! (piarries are in Passaic, Essex, Hunterdon and Mercer 
counties. The stone resembles that of Connecticut perhaps more 
closely than that of ^faryland, but nevertheless the general resem- 
blance is so close that as a rule the selling price of the material will 
be the controlling item in deciding which shall be used. 

According tn the retiirns of ihe 11th census, some <;.()10,:.'12 cu. ft. 
of sandstone were produced during the year 1SS9, valued at $.597,- 

;5on,oo. 

Delaware produces little in the way of building stone except for 
local iise. Certain gabbros and gneisses have been q\iarried for pur- 
poses of rough construction, but do not need consideration here. 

Pennsylvania. As noted above the quarry ])roduct of this state is 
large and varied. Singularly enough, however, there is little in the 
way of granitic rocks that need consideration. Good building mar- 
bles and serpentines occur in Montgomery and Chester counties and 
in both instances the stone so closely resembles that of Maryland that 
the price at which the material can be put upon the market must be 
the controlling factor of commercial importance. The ^laryland 
quarries are nearest to the markets of Baltimore and "Washington, but 
those of Pennsylvania to those of Philadelpliia and Xew York. 
Brown Triassic .sandstones, similar in a general way to those of I'red- 
erick and Montgomery ccjuntics, l)ut of a more uniform iu'own hue, 
are quarried at Hummelstown in Dauphin county, and enormous 
qiiantities of gray and blue, gray thin bedded sandstones and " blue- 
stones," used for general Iniilding and flagging, in Pike, Carbon, 
Luzerne, Wyoming and Susquehanna counties. "With tlu' exception 



86 THE BUILDING AND DECORATIVE STONES 

of the '■ Wyoming Valley " stone, as that of Wyoming county is 
commercially known, few of the latter find their way beyond the 
state limits. Blue-black roofing slates, such as must compete with 
those of Maryland, occur in the soiif-.hwesterly part of the state, in 
Berks, Dauphin, Cimiberland and Franklin counties, and also in 
enormous quantities in the northern parts of ISTorthampton and Lehigh 
counties. For many years these deposits have been systematically 
worked, the product being used for roofing, billiard tables, sinks and 
school purposes all over the United States. The statistics given below 
will convey better than words some idea of the magnitude of the 
quarrying operations here carried on. 

Granite 5,782,887 cubic feet, valued at $623,252.00;' marble, sta- 
tistics not given; sandstone 19,119,357 cubic feet, valued at $1,942,- 
979.00; serpentine statistics not given; slate 476,038 squares, valued 
at $1,541,003.00.' 

Virginia produces granites, sandstones and slates only, and as 
transportation of the quarry output is wholly by rail and there is 
little competition in the carrying trade, but little of the material 
finds its way into the general markets. The granites near Bichmond 
have been used in some of the important buildings of Washington, 
and the red-brown Triassic sandstones from near Manassas are in de- 
mand for the construction of dwellings. The statistics of the state are 
given below: 

Granite 1,073,936 cubic feet, valued at $5Sl,.s70.00; sandstone 
70,800 cubic feet, valued at $11,500.00; slate 30,457 squares, valued 
at $113,079.00. 

North Carolina. With the possible exception of one granite and 
a few Triassic sandstones this state at present produces nothing find- 
ing a market beyond its limits. There are, it is true, in the western 
half, granites in abundance, and several promising beds of marble, but 

' It is difficult to say what is included here under the name of granite, 
since there is scarcely a quarry of true granite within the state limits. 
Presumably it includes everything not otherwise classified. 

- Some $370,723 worth used for other purposes, in addition. 



MAKYLAXD GEOLOGICAL SURVEY 87 

SO far tlicy have been so little workofl tliat nothing definite can be 
said regarding them. In the southern central part of the state are 
beds of brown sandstone, the equivalents of the Triassic beds in the 
states to the nnrtlirasi. 'i'liesc have been worked spasmodically and 
the quarry product shipped to coastal cities iiu-Iuding Baltimore and 
Washington. The total output in 1SS9 so far as statistics are avail- 
able is as follows: 

Granite 708,267 cubic feet, valued at $146,627.00; sandstone 
50,001 1 cubic feet, valued at *1 2,000.00. 

So^t^h Carolina. Although there is an aluindance of granite in 
Fairfield, Tiichland, Xewbcrry, ]>e.\iugfou, Edgefield and .Vikcn coun- 
ties none of the material finds its way beyond the state limits. Mate- 
rial to the value of $5.">,320.00 i« stated to have liecn quarried in 1896. 

Georgia. This state has several ([uarries of granite, and in its 
northern portion extensive deposits of coarse crystalline granular 
building marble. This last named is coming into very general use 
for building, monumental nud interior work, even in cities as far north 
as Boston. Its consideration is thei-efore important here. A deep 
dark gray, nearly black roofing slate also occurs a: Kockuuu't in Polk 
county which is fiiuliug a slight market outside of the state. The 
statistics for 1889 as given are as below: 

(Jrauite 2,425,622 cubic feet, valued at $752,481.00; slate 3,050 
sqxuire feet, valued at .$14,s.")(i.()(i; ui irblc 25,000 square feet, valued 
at $196,250.00. 

The quarries, it should be noted, are all remote from waterways, 
and transportation is therefore limited to railroads. 

Tennessee. In this state only the .uarbles need consideration from 
our present standpoint, and these only on the supposition that at sonu' 
time the i)ropositiou may be entcu-taincd df dpcuiug u]i quarries in 
the colored uuu-bics of Carroll and Frederick counties. The Ten- 
nessee stones are dark clioci)late and white, fossiliferous, and gray and 
pink crystalline granular limestones. The latter are used both for 
general building and intcu-ior woi-k aud the first for interior work only. 



88 THE BUILDING AND DECORATIVE STONES 

Tliere are in addition to the stones above mentioned, certain otliers 
from more remote sources which, owing to their peculiar lithological 
natures, are to he found in all the principal markets of the country. 
The so-called Bedford stone or Bedford Oolites and the Berea sand- 
stones are of this type. The first mentioned of these is a very pure 
limestone but differs from those of the states above mentioned in that 
it is made u]i almost wholly of minute rounded or oval concretionary 
grains, often of almost microscopic dimensions. It is of a very light 
grayish color, sometimes almost buff, soft, very readily workable, and 
occurs in nearly horizdutally lying beds covering a large extent of 
country. It can therefore be quarried and worked very cheaply, and 
as it is, on the whole, of a pleasing color and fairly durable nature, 
it iinds a ready market in most of our larger cities. 

The second stone mentioned, that of Berea, Ohio, is a fine grained 
sandstone belonging to the Waverly series of the carboniferous forma- 
tions. This rock is an ideal " freestone " in so far as this term refers 
to working qualities, since its even granular structure and not too 
pronounced lamination permit it to be worked with the greatest 
facility in any direction. The prevailing colors are light gray to 
buff, and though from the standpoint of durability no better, nor 
perhaps so good as many stones nearer at hand, it too, on account of 
its cheapness and color, finds its way into markets at such a distance as 
would cause it to be excluded l)y cost of transportation under less 
favorable conditions. 

Reference in passing should also be made to such stones as are 
brought to our markets from foreign sources. As a very general rule 
it may be stated that the stones thus introduced are of a different type, 
so far as color and texture are concerned, from those produced locally, 
and that they are lirought in in response to the pul)lic demand for a 
greater variety. This is not, however, invariably the case since, as 
is the case with certain of the Italian marbles, easy quarrying facili- 
ties and cheapness of labor enable the producers to put the stone upon 
the American market at Iowim' rates than the domestic product, not- 
withstanding the discrepancies of distance and consequent cost of 
transportation. Xaturally a large proportion of the imported mate- 



MARYI.AXn GEOLOGICAT, SURVEY SO 

rials arc iiiarlilcs since, aside from licinc; most expensive, such are used 
verv largely in the form of thin slabs for veneering, rather than in 
solid blocks of masonrv. There are, however, a few stones of the 
granitic type, used more particularly for moinimcntal work, which 
find their way into our markets in considerable quantities. Of the 
marliles which come to our market we need mention more particu- 
larly the deep i-ed and yellow often brecciatcd varieties from Algeria, 
the so-caliod Xuiniclinn marbles; the wliit(\ lilue-gray, often veined, 
black and yellow mottled varieties from Xorthcrn Italy, particu- 
larly from ( arrai'a and Sienna; and the green or so-called Verd- 
antiqiie iiiarl)les (serpentines) from Genoa and near Prato. Stones 
very similar to these last are found in various parts of the United 
States, particularly in \'ermont, but are excluded from competi- 
tion by the high ]irices of labor prevalent in America. Stones of 
this same general nature, but of more uniform green color, occur 
in ^laryland and adjacent portions of Pennsylvania, but though from 
time to time ([uarriiMl, have never been worked upon a scale sufRcient 
to exclude the imported material even were the character of the 
marble the same. Other marbles than those mentioned, that come to 
us from abroad, are the so-called Formosa and Bougard marbles of 
(Jcrmany and tlir (Triottes of France. 

Xearly all of the granitic rocks which reach the Amei'ican markets 
from abroad are what arc known as momnnental stones. With the 
exception of those that are introduced from nearby sources, as Xew 
Bmnswick, the cost of transpoi-tation is too great to warrant the 
bringing in of materials that nni>r be sidd sufficiently cliea]) to compete 
with the native product in ordinary structural work. Among the 
more important of the gTanitcs introduced are the red and gray so- 
called .Scotch granites, from near Peterhead in Aberdeenshire, Scot- 
land. .\ coarse, ]ior]>liyritic stone, showing large pink orthoclase 
crystals in a gray groiind mass comes from Sliap in Xorthem England. 
Of greater interest on account of their beauty are a few types of 
aranitic ro(d<s that have of late Itch-u introduced into our markets from 
near Finspoug in Sonriiern Sweden. One of these is a coarse gi'anular 
aggregate of deep red feldspars and opalescent (]uartz, forming when 



00 THE BUILDING AND DECOKATIVE STONES 

polished a strikingly heantiful stone for monmnental work, and quite 
unlike anythino- now produced elsewhere. There have been also in- 
troduced from this region coarse feldspathic rocks belonging to the 
syenitic type, of a dark blue gray color, sometimes almost black, which 
are of particular interest on account of the iridescent character of the 
feldspars. They are quite similar in general appearance to the so- 
called labradorite rock from Labrador, and well adapted to interior 
decoration work. 

Besiime. We have thus enumerated briefly the possible resources 
of the coastal states with which ?ilaryland may be profitably com- 
pared. It is apparent that the future of the quarry industry must 
depend then, not so much on the kind of materials since similar kinds 
are to be found elsewhere, as on accessibility to certain markets, and 
pei'haps an ability to quarry nt such rates as will enable her to com- 
pete with others, more favorably situated, at a distance. Although 
placed at a disadvantage so far as relates to actual quarrying through 
the mantle of decomposition jiroduct that covers so much of the out- 
crops, and tlirough n lack of water transportation, the state is favored 
by a climate that will permit work out of doors for a much longer 
period than is possible in the N"orth. Differences in ])rice of lalior 
is also an item which may be taken into consideration. 

WEATHERIXG OF BUILDING STONE. 

All stones, as they lie nt and near the surface of the ground, are 
subjected to a number of agencies, in part jihysical and in part chem- 
ical, which result in a more or less complete disintegration, decompo- 
sition, or it may be temporary induration of the materials acted upon. 
Since these changes are due to atmospheric agencies, to the expansion 
and contraction of ordinary temperatures and to hydration, solution 
and oxidation brought about through meteoi'ic waters, they are all 
grciuped coiiiinuidy under the general name of Aveathering. 

Rock-weathering has been going on ever since the first rocks ap- 
peared above the ocean level. To its destructi^'e powers we are 
indebted for not merely the soil, but for the materials which make up 
the many thousands of feet of conglomerate, sandstone, shale and 
slate which occupy so large a part of the earth's surface. 



MARYLAXK (iKOI.OCJIC.VL SURVEY 91 

Tlic effects of this weatlieriiig are to-day visililc mid tlic progressive 
stages readily traeeal.le in iiirniy parts of :\raryl;iiHl ami in oilier .d" 
the states to the southward. 

Tlic \ie\vs given in Plate XiV show tlic niaiiiicr of weathering 
quite eharaetoristic of granite roeks, particidarly where su(di are trav- 
ersed hy iminerous joints. The water i>ercolating over the surface and 
filtering downward through the joints, brings about a disintegration 
and decomposition, whereby the soimd rock gives way 1o sand, y-ravel 
and clay, all very likely di.scolored by iron oxides set free tlirou<;h 
decomposition from the micas and other ferruginous silicates. Since 
on joint-blocks this weatli(>ring, which may well be compared with 
tlic r<itting of an organic iiody. would naturally take place most 
rapidly on sharp edges and corners, so these salients become gradualh- 
rounded, and an oval, bowlder-like mass of varying size results, as 
shown in the Plate XIV. It is thus that there have been formed from 
the dark colored igneous rocks the so-called " nigger-heads " so com- 
mon in many parts of tlie state. It is not necessary to here go into 
a detailed discussion of the processes and restdtant products of rock- 
weathering. Such a treatment of the nuittcr the writer has given 
elsewhere." It will be sufKcient here to say, that the results of 
prolonged weathering of granitic and allied rock> is a ferruginous 
sand and clay; of sandstones a sand, and of argillite and limestones a 
ferruginous clay. In some instances weathering nuiy be productive 
of a local induration causing soft and friable stones to become harder 
and more durable, though this is far from being a general and wide- 
spread phenomenon. In many instances the preliminaiy stages of 
weathering are manifested by a change of color, due to the whitening 
of the fcldspatliic constituent, or, as a rvdc, to the o.Kidation <il' included 
sulphides of iron (pyrite and mai'casite) or to a like change in ferrous 
carbonates or iron-rich silicates. Such changes may or may not be 
detrimental, according to local conditions. Obviously a yellow or 
brown stain from o.xidizing pyrite on a light surface like that of 
marble, is unsightly. In many lime and sandstones, however, the 
ferruginous constituents- are so evenly disseminated that the stone, 

' Itocks, Uocl'i-wi'iltlu'riii!,'- and Soils, the Miicniillaii ('()iin>an\. New York, 
1897. 



92 THE BUILDING AXI) DECOliATIVE STONES 

on exposure, assumes a niiifornily biiff or yellowish hue, which is 
known, commonly, as '" mcllowina,"' and which is not at all undesir- 
al)le. Changes of this kind arc limited mainly to light coloi'ed sedi- 
mentary rocks, and smdi as hiwv hccn qnaiTied from Ijclow the per- 
manent water level. This for the reason that exposure in the quarry 
bed above the water level has already brought about the oxidation and 
cobir change, so that when qiiarried and placed in the walls of a build- 
ing nil furtlier cliaiige takes ])lace. 

Ijiit tlie effects mited above arc mainly the products, it may be of 
geological periods, of years so many as to be quite incomprehensible 
from a human standpoint. We need consider here only those effects 
which may be brought almut liy these same agencies operating 
throughout a few score or pcrliaps bunilreds of years. 

Stone taken from the ground and exposed in the walls of a building- 
is subject to two agencies both destructive and tending toward disin- 
tegration. As already noted, the one is physical and the other chemi- 
cab 1 luring' a hot summer day, stones exposed to the direct rays of 
the sun may become, on tlii' immediate surface, heated to a tempera- 
ture of even 150° Fahr. On the going down of the sun, a gradual 
cooling takes place. In the coldest weather of winter the tempera- 
ture may sink as low as zero. iSTow, as it is well known, Jieat causes 
expansion and cold contraction. Let the reader then picture to him- 
self what here takes place. The mass of the stone is made up of an 
adnnxture of mineral particles without definite order of arrangement 
and all practically in actual contact with one another. As the tem- 
]ieratures rise each mineral expands exev so slightly and crowds 
against its neighbor; but aside from the unequal expansion of minerals 
of different species, the process is further complicated by their ten- 
dency to expand unequally along their different crystallographic axes. 
So all through that portion of the stone thus warmed there arises a 
condition of very unequal tension, which is naturally greater the 
greater the amount of heat. As temperatures fall a corresponding 
contraction takes place; but in material so granular and inelastic as 
stone the particles do not again recover exactly their original relative 
positions. Minute rifts are opened, not merely between the granules. 



MAIiVI.AXD GF.OLOOUAI, SURVEY 93 

but also along the cleavage planes of the minerals themselves, so that 
in time all cohesion is lost and the srone becomes so weak as to fall 
away to tiie (■(mdition of sand, or as is more commonly the case, absorbs 
so large an aniduut of water that when freezing ensues, disintegration 
results. Since any stone will absorb the most water along the bed- 
ding or lamination jilaues, and since too the stone is weakest, the 
cohesion of the particles least, along these planes, so it follows that 
laminated stones, like sandstones, often show signs of scaling on their 
outer surfaces even after an exposure of but a few years in the walls 
of a building. It is this form of disintegration which is so conspicuous 
and unfortunate a feature in many buildings constructed of brown, 
laiiiinafod sandstone, in Baltimore and other cities. Such a tendency 
mav b(! larc'elv overcome bv laving this stone ou its natural Ix'd, 
but any stone whatever its nature is more or less susceptible. Ina,s- 
much as stones are but poor conductors of heat, that is, as the heat 
penetrates but slowly, and to biit slight depths, such a f(jrm of 
disintegration is limited to the immediate surface. Where, however, 
the disintegrated material is removed so soon as formed, the process 
may go on indefinitely until a finely carved front or cornice may be 
entirely nnned. 

It follows from the above tliat, other things being equal, a stone in 
which the various mineral particles are closely interknit will lie more 
durable than one of granular structure. 

One of the most serious of the destructive agencies to which stone 
in the walls of a building are subjected is the freezing of absorbed 
water. All stone as they lie in the ground contain more or less mois- 
ture or quarry xcater, as it is called, which in time dries out after the 
stone is quarried. More water is however likely to be absorbed on 
exposure to rains, and since water in freezing exerts an expansive force 
equal to some 150 tons to the scjuare foot it may be readily undi-r- 
stood that if the amount of moisture contained in the pores of a stone 
is at aU large, serious disintegration may result. It is to this cause 
that is largely due, as already noted, the scaling and crumbling of the 
brown sandstone so commonly used in house construction througliout 
the Eastern United States. Other things being equal again, a stone 



94 



■JIIE BUILDING AKD DECORATIVE STONES 



possessing low absorptive power will be more durable in moist, tem- 
perate and frigid climates than one that will absorb a large amount. 
Figures showing the relative amount of water absorbed by stones of 
various kinds are eiven in the followiii"- table. 



ABSORPTION TESTS I. 



Klnil of SKiue. 
Marble, Cockeysville, 

Suudstriue, Seneca, 

Granite, Port Deposit, 

(iranite, Woodstock, 

Gneiss, Baltimore, 

Sandstone, Taneytown, 
Quartzite, Eminitsburg, 



Wgt. after 

drying 24 

hours at 

212 F. 


Wgt. after 

IniTiiersion 

24 hdurs in 

water. 

Grams. 


Gain in 
weight. 
Grams. 


Percentage 

of 
absorption. 


367.1.5 


367.93 


0.78 


0.312 


367.07 


367.86 


0.79 


0.315 


313.35 


331.38 


7.93 


3.530 


313.7.5 


331.18 


7.43 


3.368 


351.33 


353.33 


0.S9 


0.3.53 


341.34 


343.00 


0.66 


0.196 


340.43 


341.31 


0.88 


0.358 


340.45 


341.34 


0.79 


0.332 


3.54.37 


355.07 


0.70 


0.197 


323.36 


336.97 


3.61 


1.116 


320.33 


334.05 


3.83 


1. 196 


347.58 


347.87 


0.29 


0.083 



ABSORPTION TESTS II. 



Marble, Cockeysville, 
Sandstone, Seneca, 
Granite, Woodstock, 
Gneiss, Baltimore, 
Sandstone, Taneytown, 
(Juartzite, Eminitsbiirs;, 344. .50 



Wgt. air 

dry. 
Grams. 


Wgt. after 

Immersion 

one liour. 

Grams. 


Wgt. after 

immersion 

one day. 

Grama. 


Wgt. after 

immersion 

one weeli. 

Grams. 


Galu in 
wgt. 
Grams. 


Percent- 
age of ab- 
sorption. 


367.35 


307.30 


.367.60 


367.60 


0.35 


0.09 


1003.70 


1007.70 


1010.80 


1011.70 


8.05 


0.07 


34.5.00 


345.. 50 


34.5. .50 


34 .5. .55 


0.05 


nil 


3.50.70 


350.65 


3.50.70 


3.50.67 




nil 


329.60 


330.. 50 


330.90 


331.55 


1.95 


0..59 



344. .50 



344.. 50 



344.85 



0.35 



0,10 



In the second set of experiments which were conducted by Dr. 
Mathews, the blocks were all of the same size (two inches cube) as 
those of the first set, except in the case of the Seneca sandstone, where 
a block four inches square and one and a half inches thick was em- 
ployed. The weighings were made after the blocks had been swabbed 
until no glistening water remained. These tests show that little water 
is taken up by the specimens beyond that carried after remaining over 



MAKYI.ANl) GKOLOOICAL SURVEY 95 

a yoai' in tlif wariii air of an otHce. 'I'lic wcatiici- diiriiifi- the cxjieri- 
iiicutiiii;' was wanu (85°-95° F. ), and the limnidity was approxiuiatflv 
seventy per cent. 

Tlie water wliieli comes to the earth in rainfalls is never absolntcdy 
jiure, bnt contains a variety of mechanically and chemically admixed 
iiiijiiiritics. ^Xmoni: ihc (•li(iiii<'ally .nlmixed, or dissolved ini|niritics, 
which arc the only ones that need here he considered, carbonic acid 
is the must widespread and abnndant, while in smaller anioniits and 
])articularly near large cities there may be traces of hydrochloric and 
sniplniric acids. These all arc cajiablc of exerting a solvent action 
on the iiialci-ial composing imilding stone, particularly (in lime car- 
bonate. The aniotint of material that will be dissolved during a single 
shower may be infinitesimal, or during a year scarcely np])rcciable. 
^'et there are many stones, p.ii'ticnhirly those composed of ptire lime 
carlHinate (limestones), or of siliceous grannies cemented by lime 
carbonate, whicdi in time suffer severely. The ronghened surface 
and loss (d' polish seen so fre(]nently (m marble tombstones and exterior 
work of any kind is nsnally due to this solvent action of rain water 
and its dissolved acids. • 

The adajitability of a stone for strnctnral purposes depends then, in 
no small degree, n])on its weathering qualities, that is to say tipon its 
power to withstand for cenlin-ies even, exposure in iiie walls of a 
building, without serious discoloration, disintegration or solution. 
Let us now take into consideration these weathering (pnilities as dis- 
l)layed by the various types of rocks, although a full disctission of the 
subject mtist h(" left for moi-e I'omprehcnsive treatises.' 

Granites and gneisses possessing very low ratios of absorption (see 
table above) and lieing made up so largely of silica and silicate 
minerals, are very little all'ected by freezing and solution. The chief 
causes of disintegration with rocks of this class, are temperature 
changes, such as pi'oducc^ grantdation. Aside from a weakening of 
the cohesion ]iower between ti:e individual constituents, the feldspars 
may split up along cleavage lines, and a disintegration follows which 
may be sufficiently evident to catise small spawls to fall along the 

'See Kocks. i;o<-k-\vcatluTini>- and Soils, the M.acmillan Company. Xew 
York, and Stones for Bnildiiiir and Decoration, Wiley and Sons;, N'ew York. 



96 THE BUILDING AND DECORATIVE STONES 

joints between the blocks, or perhaps to ruin fine carvings. In some 
instances deleterious minerals like pyrite may be present in sufficient 
quantity to cause unsightly discoloration. 

All tilings considered, n fine grained liomogeneons rrick will 1)P 
found more durable than one that is of coarser grain. Also a rock 
in which the individual particles are closely interkuit, dovetailed to- 
gether, as it were, will resist disintegration longer than one that is of 
a granular structure at the start. 

Serpentines are likewise only slightly absorptive and when homo- 
geneous little affected by solution. Nearly all serpentines of such 
quality as to be used as verdantique marble contain, however, veins 
and spots of calcite, dolomite or magnesite, and many dry seams. 
Such rocks, therefore, weather unevenly, lose their polish, and may 
shortly crack and split along these dry seams when exposed to tlie 
weather. These marbles should then be used only where protected 
from the weather. Crystalline limestones and dolomites (marbles) 
are extremely varialile in their weathering qualities, are likely bo 
carry pyjite, and great care needs always be exercised in their selec- 
tion. A limestone marble, i. e. one composed essentially of lime 
carbonate, is likely in time to suffer from solution whereby corners 
become rounded, surfaces roughened and perhaps inscriptions oblit- 
erated. The mechanical agencies are here also operative as in granite, 
so that, as a rule, a stone of this class is less durable than a good 
granite. The pure white stones are, as a rule, more granular and 
weaker than the gray and blue gray. Dolomites being less soluble 
than limestones might at first thought seem promising of greater dur- 
ability than the limestones. Unfortunately this is not altogether the 
case, since such stones often possess a more granular structure thau 
do limestones, and hence suffer more from disintegration. Indeed a 
dolomitie marlik- can, nut infrequently, lie distinguished from one of 
pure limestone, simply from the way it weathers iu the natural out- 
crop. In the case of the dolomite, the surface of the outcrop may be 
found covered here and there with a sand composed of angular parti- 
cles which results merely from the mechanical disaggregation of 
the stone, while in the second case the stone loses almost wholly liy 



MAUYLAXD GEOLOGICAL SLEVEY 



97 



solution, and we find it passing superficially into a clay without the 
production of sand. 

The light colors cliaracteristic of most marbles render iron stains 
peculiarly objectionable, and as pyrite is a very common constituent 
of such rocks, much care is necessitated in its selection. The ordi- 
nary unmetamorphosed limestones, like the deep blue-gray varieties 
from the Trenton formation are scarcely at all absorptive, and weather 
fairlv well, Imt tlioir sombre colors are somethine; of a drawback. 




Fifi. U. — Pliotiimicnurrapli of Scnecii Samlstone (masriiitii-il ten diameters). 



Sandstones, on account of the widely varying character of the 
materials of which they are made up, variation in texture, degrees of 
porosity, etc., are perhaps as a whole more variable in their weathering 
qualities than any other class of rocks. In order to fully appreciate 
this variability, we must remember that we have to do here with what 
are but beds of indurated sand; that these stones are made up of sand 
7 



98 THE BUILDING AND DECORjVTlVE STONES 

particles lield together by simply being closely compacted by finer 
material, or by means of a cement composed of lime carbonate, iron 
oxides or silica (see Fig. 14). Where the sand is loosely compacted, 
or the sand grannies are interspersed with much finer, clayey matter, 
the stone will absorb comparatively large amounts of water and is 
likely to become injured on freezing. Where the cementing matter 
is carbonate of lime, rain water trickling over the surface is likely to 
remove it in solution, leaving the stone to fall away, superficially, to 
the condition of sand once more. Ferruginous cements are likewise 
slightly affected, though in a much less degree. The siliceous cement 
is least affected of all, and provided the amount of induration be the 
same, a purely siliceous sandstone, cemented by a siliceous cement, 
is one of the most indestructible of building materials. 

Many sandstones have a distinctly laminated structure; that is, their 
jiarticles are laid down in parallel layers, differing somewhat in size, 
color and degrees of compactness. The result is that some layers will 
absorb more water than others and the rock will undergo a splitting 
up into thin flakes. When such a rock is stood on edge in the walls 
of a building and the water filters do\vn along these porous layers and 
there freezes, serious results follow, particularly when the stone is 
carved. Pyrite is a common constituent of sandstones, particularly 
the gray varieties, and is likely to prodiice staining. Its presence 
needs to be looked for with care. A fine-grained sandstone is often 
fully as absorptive as one that is coarse, and fully as likely to injure 
from freezing. A ratio of absorption of more than 4 per cent by 
weight must be regarded as unfavorable. 

Eoofing slates or argillites represent as a rule the indurated qnd 
otherwise changed argillaceous products of the weathering, or rotting 
as we might say, of pre-existing rocks. They are in short made up 
from the most indestructible of natural materials, and on first thought 
might themselves seem indestructible. Unfortimately those capable 
of being split sufiiciently thin for roofing purposes are not in all 
cases indestructible, nor are they equally resisting in all parts. In 
nearly all slates there are to be found dark colored bands or ribbons, 
containing deleterious minerals like pyrite or marcasite, wliich are less 



MAKYLAXD GEOLOGICAL SUKVEY 99 

durable than are the other portions. Moreover the exposed position 
of slates, when on a roof, is such as to try to the utmost their lasting 
qualities. 

It is here that the extremes of temperature are greatest and the acid 
action of rains most manifest. It is little to be wondered at therefore 
that in time the slates become brittle and break, or at least crack, a 
condition of affairs soon indicated by leaking. A slight fading in 
color is also a not uncommon feature of many slates, the exact cause 
of which does not seem to be yet fully apparent. 

Methods of Testing Building Stone. 

How to ascertain liv any series of lests that can be performed in a 
laboratory the durability or general suitability for construction of 
any stone is a problem with which builders have long struggled and 
which is yet far from solution. 

In order to !i]iprociate the difficidty in thr ])rolilciii, let us liriefly 
recapitidate. 

Stone in the walls of a building is exposed to the chemical action 
of the atmosphere, the physical action of temperature changes and to 
the crushing and shearing forces incidental to its position in the wall. 
Satisfactory tests, then, must .show the ability of the stone to with- 
stand to-day any of the agencies enumerated above, and must also 
indicate its ability to withstand them after years of exposure. 

A stone which to-day will withstand effectively any of the tests 
which can be a])p]icd may, through the prolonged action of external 
agencies, become so weakened as to be valueless or so discolored as to 
be unsightly. 

In this chapter it is proposed to give a general summary of the tests 
which have thus far been applied, to show in how far they are suc- 
cessful, and to make such suggestions as seem pertinent to the subject. 
It will not be necessaiy to give in full all the details of these tests, 
as they have from time to time been made. It will be sufficient, 
rather, to refer only to such as are historically interesting or of value 
on account of the results they may have yielded. 

(1) Tests to ascertain permanence of color. The change of color in 
a rock, on exposure in a biiilding, is due mainly to a change in the 



100 THE BUILDING AND DECORATIVE STONES 

form of combination of the iron. Rocks taken from below the water 
level often carry iron in the form of protoxide carbonate (Fe CO3) or 
pyrite (Fe S2). Either on exposure to the air is likely to become oxi- 
dized as noted under the head of weathering. The tests that can be 
applied in the laboratory are made (1st) to ascertain the presence of 
sulphur, indicating pyrite, and (2nd) the effects of an artificial atmos- 
phere in accelerating oxidation. 

The following is the method for this last mentioned test as adopted 
by Prof. J. A. Dodge.' 

The specimens tested were rectangiilar in outline, and from an 
inch to an inch and a half in diameter. These were dried in a water 
bath (temp. 212° F.) till all the absorbed moisture was expelled, 
cooled and weighed. They were then placed upon a set of glass 
shelves standing in a porcelain pan containing strong muriatic (hydro- 
chloric) acid. 

An open bottle containing nitric acid, and one containing hydro- 
chloric acid and black oxide of manganese were placed close by, and 
the whole covered by a bell glass, foi-ming an air-tight chamber. 
The fumes from the acids, together with the chlorine fumes from the 
manganese and hydrochloric acid, filled the chamber and exercised 
a powerful coiTosive and oxidizing effect on the samples. After a 
period of seven weeks the stones were removed and washed, and the 
change in color, if any, noted. A similar series of tests was made by 
Prof. A. Wendell Jackson in 1887 on California building stones,' and 
the efficiency of the method seems fairly well established. 

(2) Tests to ascertain resistance to corrosion. The question to be 
settled here is one relating chiefly to calcareous rocks, to limestones 
and marbles, or to sandstones containing a calcareous cement. The 
most satisfactory method available, is apparently that of Prof. Dodge, 
given in the publication above referred to, which is as follows: 

A set of pieces of essentially the same size and shape as those used 
in the last mentioned tests were selected and dried and weighed in 
the same manner. These were then suspended by strings in a glass 

' Final Report Geological and Natural History Survey of Minnesota, vol. i, 
1873-83 (1884), p. 185. 

= Seventh Ann. Keport State Jlineralogist of t'a]., 1887 (1S88), p. 205. 



MARYLAND GEOLOGICAL SURVEY 



VOLUME II, PLATE VI. 




KKAGMl'iXTS ()!■■ r.rul'JS AKiKK CltlJSli I \r.. 



1L4.EYLAND GEOLOGICAL SURVEY 101 

vessel of water, not in contact witli one another, and a stream of car- 
bonic acid gas was run through the water for several hours at short 
intervals, so as to keep the water pretty well saturated. The gas was 
washed before entering tlie vessel containing the stones, and the water 
in the vessel was changed every few days by means of a siphon. The 
action was continued for a period of six weeks, when the specimens 
were removed, washed in pure water, dried and weighed. Tlie differ- 
ence between the first and second weighing indicated the amount of 
material dissolved by the carbonic acid water. Tn the case of some 
limestones this was found to be over 1 per cent, though as a rule much 
less, and in the case of some granites so small as to be scarcely appre- 
ciable. 

(3) Tests to ascertain resistance to abrasion. Tests of this nature 
are necessary only in cases where, as in steps and walks, the material 
is subject to the friction of feet, or where as in dams and breakwaters, 
it is subject to the action of running water and waves. In some in- 
stances it is ]iossible that stones may be so situated as to be subjected 
to the action of windblown sjind. In the selection of Belgian blocks 
for street pavements, it is naturally an important matter. 

The resistance to wear, it may be stated, depends not more, perhaps 
even less, upon the actual hardness of the constituent particles of a 
stone, than upon the firmness with which they adhere to one another. 
This is well illustrated in the case of many sandstones, which though 
made up of the hard and difiicultly destructible mineral quartz, are so 
friable as to be practically worthless. In making a series of tests of 
this nature, it is well to consider the uniform as well as actual hard- 
ness of the stone. Many stones wear unevenly, owing to their une- 
qual hardness in various parts, and are even more objectionable than 
though uniformly soft throughout. The serpentinous steatite used 
many years ago for steps and sills in Philadelphia wore very unevenly 
owing to the siiperior hardness of the serpentine over the steatite, 
causing the former in time to stand out like knots in decaying logs. 
The power of any stone to resist abrasion can in the writer's belief, 
and as he has elsewhere ' stated, be ascertained by observing the 
manner in which it works under the chisel. 

' Stones for Building- and Decoration, 2ud Ed., p. 445. 



102 THE BUILDING AND DECORATIVE STONES 

Resistance to the action of windblown sand could readily be ascer- 
tained by subjecting prepared samples to the action of an artificial 
sandblast such as is used in the Tilghman process of stone caridng. 
A fairly accurate idea of the resistance 1o actual wear can be obtained 
by the rate at which the samples can be ground down on a common 
grinding bed. It is diificult to perfect this method, since so much 
depends on the weight applied and the constancy of the supply of 
emery, sand or whatever may be the cutting medium. 

(4) Tests to ascertain the absorptive powers. These tests have a 
direct bearing upon those which are to follow, since it is largely 
through freezing of absorbed water that cold produces disintegration. 
The test of the absorptive poAvers is therefore one of the most import- 
ant, and for a single test perhaps the most conclusive of any, as the 
writer has also elsewhere stated.^ For reasons noted below it cannot 
be relied upon altogether. 

There are two absorptive tests commonly made; the one to deter- 
mine the absorption of moisture from a damp atmosphere, and the 
other the amount of absorption of water through actual soaking. Of 
the two the last is by far the more important. 

The method of determining the absorption from a damp atmos- 
phere as carried out l)y Prof. Dodge" is as follows: 

The samples of stone Avere placed in the cells of a hot-water bath for 
several days, to expel their hygToscopic moisture, after which they 
were allowed to cool in desiccators, over sulphuric acid, and weighed. 
They were then placed upon a set of glass shelves standing in a pan 
of water, and a tight cylinder was inserted over the shelves, the mouth 
of the cylinder being sealed by the water, after the manner of a gas 
holder. The apparatus remained thus in a room the temperature of 
which was pretty uniform (from fiC to 70° Fahrenheit) for seven 
weeks, the water being replenished from time to time so as to maintain 
a constant closure of the cylinder. The stones were then removed to 
bell-jars in which they were supported over water, and thus taken to 
the balance and weighed. The samples submitted to this test were 
somewhat larger than those used for making the determination of 
specific gravity. They had an a^^'erage weight of about 70 grammes, 

' Op. cit., p. 439. - Op. cit., p. 1S5. 



SIAUVLAND GKOLOGICAL SURVEY 103 

and were roiiplily shaped. The ininiimnii absorption of moisture .03 
per cent of the weight of the stone, is so small in amoimt as to be 
practically nothing. The maximum 3.94 per cent of the weight of 
the stone seems qnite considerable. It seems probable that, in the 
atmosphere saturated -n-ith moisture in which they were kept for seven 
weeks, some of the stones absorbed all the moisture they were capable 
of taking up, while others by a longer exposure to the same conditions 
would Jiave shown still higher figures. 

In determining the amount of absorption by soaking it is best to 
have the specimens as nearly rectangular as possible, with faces 
ground smooth, and for purposes of comparison as well as for possible 
subsequent use in other tests it is well to have them approximately in 
the form of 2-inch, culies. These should be thoroughly dried and 
weiglied, as in the tests previously mentioned and placed in a porce- 
lain dish with sufficient water to cover them and allowed to stand until 
fully saturated — say a period of 3 or 4 days at least. The cubes sho\d»l 
then be carefully removed, the water absorbed from tlie immediate 
surface by means of blotting or any form of bibulous paper, and 
then weighed. The drying and weighing should be accomplished 
with as little delay as possible, to avoid loss by evaporation. The in- 
crease in weight of the cubes is of course due to the water absorbed, 
and tlic percentages can thus be readily calculated. The results of a 
few tests of this nature are given on p. 94. As here shown, and as 
an almost universal ride, the sandstones are the most absorptive. It 
may be said further, that the absorption takes place most rapidly and 
in the largest amounts along the bedding planes. While the absorp- 
tion of more than 3 or 4 per cent of water is a matter that can as a 
rule be regarded as detrimental, still it does not necessarily follow 
that such a stone will siifFer most on freezing. This for the reason 
that a coarsely porous stone will dry more quickly than one of finer 
grain and moreover the size and shape of the interstitial cavities is 
such that the expansive action of freezing water finds relief without 
forcing apart the granules as noted below. It is sufficient to note here 
that a high rate of absorption is more detrimental to a fine than a 
coarse grained stone, and also that experiment has indicated that such 



104 THE BUILDING AND DECORATIVE STONES 

stones are weaker, will crush under less load, wlien saturated with 
water than when dry. 

(5) Tests to ascertain resistance to freezing. The power of a 
stone to resist the action of frost is naturally largely dependent upon 
its absorptive qualities, as noted above, since it is the freezing of the 
absorbed moisture that produces disintegration. It has been shown 
that water passing from the liquid to the solid state, that is to the con- 
dition of ice expands in the proportion of 100 to 109. That is to say, 
an amount of water occupying 100 cubic inches before freezing must 
occupy 109 cubic inches after. The pressure exerted by this expan- 
sion is equal to 150 tons for each square inch of surface. Provided 
then the interstices of a stone are filled with water, Avhich there 
freezes, it is easy to see that if there is no other way of relief, the 
stone must be sadly disrupted. Abundant evidences of this are to be 
found in any sandstone quarry that has been closed during the winter 
months without protection. That the result is not more marked than 
it is, is due to the fact that relief is found in the expansion outward 
through the pores of the stone. It is for this reason that a coarsely 
porous stone will often stand a freezing test better than one that is 
of fine grain, the expansive force finding relief outward through the 
larger pores. 

The importance of the freezing test was early recognized, and 
several methods have been devised for making such in the laboratory. 

Obviously, the best method to pursue is that of nature, and to 
actually submit the samples to repeated freezings and thawings. Un- 
fortunately this can not at all times be readily done, and moreover 
nature's methods are sometimes s1oa\', so that other schemes have been 
proposed with a view of showing the relative rather than the actual 
powers of resistance of different stoues. Perhaps the best known 
method of determining the resisting power of stones is that pro- 
posed by Brard A^-hich consists in saturating the stone with a solution 
of sulphate of soda which on crystallizing expands as does water on 
passing into the condition of ice. A modification of Brard's original 
process was used by Mr. C. G. Page with reference to the selection 
of material for the Smithsonian Institution l)uilding' in Washington.' 

' See Hints on Public Architecture, p. 119, by R. D. Owen, also Stones for 
Building and Decoration, p. 439. 



JIAKVI.AXD GEOI.OOIf.VI, SUKVKY 10') 

Tlie jirocess as carried on by [Mr. I'aoe consisted in builiiiji a carefully 
l)repared and weighed CTihe, for half an hour, in a saturated solution 
of the sulphate, and then allowing it to dry, during which process the 
absorbed salt crystallized and expanded. Although the results were 
found to be not in all cases quite reliable, and evidence was deduced 
to the effect that the boiling salt solution exercised a chemical as well 
as mechanical action, still tlicy are not without interest and may be 
given ill talinlar form as below. 

Specific 1,088 In 

.Malerliils. Kravlly. trrnlns. 

Marble, close-drained, Maryland '2.834 0. 1!) 

Marble, coarse "alum stone," Baltimore County, Maryland... 2.8.57 0..50 

Marble, blue, Maryland 2.(113 0.34 

Sandstone, coarse, Portland, Connecticut . . 14.3f> 

Sandstone, tine, Portland, Connecticut 2..5S3 24.93 

Sandstone, red, Seneca Crceli, .Maryland 2.073 0.70 

Sandstone, dove-colored, Seneca Creek, Maryland 2.4Sfi 1.78 

Sandstone, Little Falls, New Jersey . . 1..58 

Sandstone. Little Falls, New Jersey 2.482 0.02 

Sandstone, coarse. Nova Scotia 2. .518 2.16 

Sandstone, dark, coarse, Seneca Aqueduct, Peters's quarry ... . . .5.(i0 

Sandstone, Acquia Creek, Virginia 2.230 18.00 

Sandstone, 4 miles above Peters's quarry. Maryland . . 0..58 

Sandstone, Beaver Dam quarry, Maryland . . 1.73 

Granite, Port Deposit, Maryland S.CO'.I .5.05 

Marble, close-grained, Montgomery County, Pennsylvania.... 3.727 0.35 

Limestone, blue, Montgomery County, Pennsylvania 2.009 0.28 

Granite, Great Falls of the Potomac River. Maryland . . 0.35 

Soft brick 2.311 10.46 

Hard brick 2.394 1.07 

Marble, coarse dolomite, Monnt Pleasant, New York 3.800 0.91 

The specimens operated upon, it should be stated, were cut in the 
form of inch cubes. Each was immersed for half an hour in the 
boiling solution of sulphate of soda, and then hung up to dry, this 
perfonnance being repeated daily throughout the four weeks which 
the experiment lasted. 

Although as above noted this process is practically abandoned, the 
series of tests given was productive of certain results wliich are well 
worth a moment's consideration. Thus the red sandstone from Seneca 
(^reek, [Maryland, with a spc'cific gravity of 2.672, or a weight per 
cubic foot of 167 pounds, lost by disintegration but 0.70 grains. This 



TOG THJD BUILDING AND DECOEATIVE STONES 

was the stone ultimately selected for the Smithsonian Institution 
building, and the structure as a whole is to-day probably in as good a 
state of preservation as any of its age in the United States. The 
second stone, from Acquia Creek, Virginia, with a specific gravity 
of 2.23, or a weight per cubic foot of but 139.37 pounds, and which 
lost 18.6 grains is the one in the construction of the White House 
and the old portions of the Capitol, Interior Department and Treasury 
buildings. This stone has proven so poor and disintegrates so badly 
that the buildings are kept in a condition anywise presentable only 
by repeated applications of paint and putty. The results obtained 
with hard and soft brick are also very striking; the one weighing at 
the rate of 138 pounds per cubic foot, losing 16.46 grains, while the 
harder brick, weighing at the rate of 143 pounds, lost but 1.07 grains. 
If anything can be learned from the series it is that with substances 
having the same composition, those which are the most dense — which 
are the heaviest bulk for bulk — will prove the more durable. The 
results obtained on coarse and fine varieties of Portland sandstone 
suggest at least that water would freeze out of the coarser stone, and 
therefore create less havoc than in that of finer grain, a probability 
to which I have already referred.' 

More recently this method has been reinvestigated by Dr. L. McI. 
Luquer " with a view of ascertaining what relation may exist between 
the sulphate of soda and the freezing methods when both are caiTied 
on under the same conditions. In these tests recognition is taken of 
the fact broiight out a generation or more ago to the effect that a 
hot solution of a sulphate of soda is likely to undergo decomposition 
and give rise to free alkali (NaaO) which exerts a powerful chemical 
effect and weakens the cohesive power of the granules. The method 
employed, as given in the paper above referred to, was as follows: 

The specimens, which had been carefuUy prepared, biiished, dried 
and weighed, were boiled in the sulphate of soda for half an hour, in 
order to get complete saturation, jit the end of the half hour it was 
noticed in every case that the solution was slightly alkaline, although 
at the start it had been neutral. In order to prevent any continued 

' stones for I'.iiililiiig' and Decoration, :.'cl ed., p. 438. 
' Trans. Am. Soc. Civil Engineers, Mar. 1895, p. 2:)"). 



MARYLAND GEOLOGICAL SURVEY 107 

chemical action the beakers were emptied, the specimens rapidly 
washed with water, and the beakers immediately refilled with the 
neutral siilphate sohitiou. After soakins^ for several hours the speci- 
mens were hung up l^y threads, and left for 12 hours (during the 
night) in a dark room. 

In the morning all the specimens were covered with an efflorescence 
of the white sulphate of soda crystals; ihey were then allowed to soak 
in the solution during the day and again hung up at night. Efflores- 
cing for about 12 hours and soaking for about the same time constituted 
a period. The experiments lasted for eight periods, and were con- 
ducted in this way in order to make them correspond with those made 
with freezing water, as in the cold-storage room the specimens could 
only be changed night and morning. 

In two cases the specimens were allowed to effloresce for 36 instead 
of 12 hours, to insure thorough action of the salt. The experiments 
thus really lasted for 10 days. It was deemed that eight periods or 
days were sufficient, as de Thury states that if a specimen is acted on 
by this method of testing, the cfFect wiJl be noticed in five days. 
The general opinion of others seems to be also, that a week or eight 
days is long enough to obtain good results. During the test the solu- 
tion was renewed from time to time, and appeared to remain neutral. 
The temperature of the room varied from 60° to 70° Fahr. (18° to 
21° Cent.). Those specimens most affected began to show the dis- 
integrating action of the solution very early in the course of the 
experiments. At the end of the 10 days the specimens wore sprayed 
with the stream from a wash bottle to remove any adhering particles, 
washed in water to remove the sulphate of soda, carefully dried in 
an air bath at about 120° Cent., and weighed again. 

The difference between the weights was taken as the loss due to the 
action of the sulphate of soda. The results are given in tabular form 
below. 

In the experiments of Prof. Bodge ' carefully prepared cubes the 
dry weight of which had been previously ascertained were placed in 
a shallow iron pan, nearly covered with water and exposed to the 
open air, but in a sheltered place, to freezing and thawing, for a period 

' Geol. and Nat. Hist. Survey of Minnesota. Final Reports, vol. i, p. ISCi. 



108 THE BUILDING AND DECORATIVE STONES 

of 8 weeks during February and ]Marcli. To thaw, the specimens 
were occasionally brought into a Avarm room for a few hours. After 
the exposures, the pieces were carefully examined, then dried for six 
days and weighed, the difference between the first and second weight 
indicating the loss of material by the frost action. In the freezing- 
experiments by Dr. Luquer, above referred to, the specimens were 
allowed to thaw and soak in water during the day, and were hung up 
and frozen at night. The experiments lasted the same number of 
periods as did the sulphate tests. The temperature of the cold room 
in which the freezing was carried on varied from 4° to 10° Fahr. and 
that of the room in which the soaking and thawing was done, 85° 
Fahr. After the freezing the specimens were allowed to soak in 
water for the same period as did those used in the sulphate of soda 
experiments, after which they were dried and weighed. During the 
progress of the experiments, it is stated the deterioration was so slight 
that the effect was scarcely noticeable, the sandstones only showing 
the effect of a slight residue in the bottom of the pails in which the 
experiments were performed. Below are given in tabular form the 
results obtained by both processes. It will be noted the action of the 
sulphate was by far the most energetic, but it cannot be learned that 
there is any definite relationship. Hence all things considered it 
seems best that the sulphate method be abandoned, and the actual 
freezing test always resorted to. 

Eesults of Experiments with Sulphate of Soda. 

Original Loss of Losp of 

■weight in weight, in weight in 

No. SiJecimens tested. grams. grams. parts in lu.oOO. 

1 Coarse crystaUine dolomitic marble 71.9030 0.0775 10. 7S 

■2 Medium crystalline dolomitic marble !)3.8861 0.1.597 17.01 

3 Fine-grained limestone 67.0964 0.1744 35.99 

4 Coarse-grained red granite 71.8648 0.1115 15.51 

5 Medium-grained red granite 56.4939 0.0370 6.55 

6 Fine-grained gray granite 43..5910 0.0335 .5.16 

7 Rather fine-grained gneiss 61.8687 0.0393 6.33 

S Norite, "Au Sable" granite 3.5.1173 0.0135 3.84 

9 Decomposed sandstone 39.4394 1.9010 483.13 

10 Very fine-grained sandstone 37.77G0 0.1800 47.65 

11 Sandstone 38.0335 0.4070 14.5.18 

13 Pressed brick 37.4035 0.0930 34.86 

51 Decomposed sandstone 33.9660 3.7335 1 631.31 

53 Sandstone 33.9001 0.1381 57.78 



MARYLAND GEOLOGICAL SURVEY 109 

Results of Experiments with Frost. 

Orlslnal Loss of Lose In 

„„ _ , wclBlil In wclEht 111 wclBtit In 

"O. Specimens tested. craiiis. criinis. parts In lO.OCO. 

1 Coarse crystalliue ilolomitic marble 63.6407 0.0197 3.10 

2 Medium crystalline dolomitic marble. .. . 93.08.il 0.0316 2.30 

3 Fine-i^rained limestone .55.2787 O.Oll.j 3.07 

4 Coarse-grained granite .52.2787 0.0072 1.38 

.5 Medium-grained red granite 03.4693 0.0113 1.70 

6 Fined-grained gray granite .58.0149 Very slight, 

about same as 
No. .5. 

7 Ratlu-r liue-grained gneiss .53.7260 Very slight, 

about same as 
No. .5. 

8 Norite, ''Au Sable" granite 44.4665 Very slight, 

less than 
No. 5. 

9 Decomposed sandstone 38.4055 0.3640 08.74 

10 Very tine-grained sandstone 39.5130 0.0430 10.6:! 

11 Sandstone 31.9437 0.0312 14.21 

13 Pressed brick 37.1790 0.0255 6.86 

51 Decomposed sandstone 34.1020 0.0610 2.5.31 

53 Sandstone 20.2385 0.0180 8.89 

(6) Tests to ascertain ratio of expansion and c-ontractiuii. Tests of 
this nature are of value for tlic purpose of (1st) making proper allow- 
ance for expansion in parapet walls, and similar situations, and (2nd) 
because through expansion the tenacity of the stone is weakened. As 
long ago as 1832 Col.Totten, in view of the difficulty of making perma- 
nently tight joints even with the strongest cements, instituted a series 
of experiments to ascertain the actual expansion and contraction of 
granite, sandstone and marble when subjected to ordinary temperature. 
He found the rate per inch for each degree of temperature for granito 
to be .000004825 inch: fnr marble .000005668 inch, and for sandstone 
.000009532 inch. That is to say a block of stone one foot in length 
raised from a temperature of freezing (02°) to that of a hot summer 
day, say 90°, would be expanded to the amount of .005416 inch or 
would be 1.005416 inches in length. The amount is apparently 
trifling yet it produces a weakening efl'cct wbicli is of both (■(•(.nnniii- 
and geologic significance. 

Within recent years some good work in tliis line has lieen done 
under the direction of the Ordnance Pepartmeut of the U. S. Army. 



110 THE BUILDIKG AND DECORATIVE STONES 

The method of testing has consisted in placing carefully measured 
bars of stone in baths of cold -water (32° F.), hot water (212° F.), and 
back to cold water once more. It was noted that in none of the 
samples tested did the stone quite regain its first dimensions on cooling 
but showed a slight " permanent swelling." Since this can only mean 
that the particles composing the stone have separated though ever so 
slightly, it is an important matter as it necessitates a weakening which 
is shown by actual pressure tests. The tables given below show the 
amount of permanent swelling occurring in stone bars of a gauged 
length of 20 inches.' 

Oranites. 

Amount of 
Description. permanent 

swelling. 
Inch. 

From BracUlock quarries near Little Rock, Ark. ^Ligbt) 0048 

From Braddock quarries near Little Rock, Ark, (Dark) 0034 

From Millbridge, Maine, White Rock Mountain 0033 

From Broad Rock quarry, Chesterfield County, Virginia 0047 

From Korah Station, Virginia 0048 

From Exeter, Tulare County, California 0019 

From Rockville, Stearns County, Minnesota 0061 

From Sioux Falls, Minnesota 00.59 

From Troy, New Hampshire 0031 

From Branlord, Connecticut 0043 

.0033 
From Milford, Massachusetts 0071 



Mean 0040 

MarUes. 

Amount of 
Description. permiinent 

swelling. 
Inch. 

Rutland, white, Vermont 01.3.5 

Rutland, white, Vermont (second exposure) 0029 

Mountain Dark, Vermont 0064 

Sutherland Falls, Vermont 0107 

From St. Joe, Searcy County, Arkansas 0196 

From De Kalb, St. Lawrence County, New York 0055 

From Marble Hill, Georgia 0077 

Mean 0090 

'■ Rep. on Tests of Metals, etc., at Watertown Arsenal, U. S. War Dept., 
1895, p. 322-23. 



MARYLAND GEOLOGICAL SURVEY 111 

Limestones. 

Amount of 
Descrlpllon. permanent 

(iwelUnK. 
Inch. 

From Isle La Motte, Vermont OOSl 

From Wasioja, Minnesota 0024 

From Fort Riley, Kansas 00.">3 

From Beaver, Carroll County, Arkansas 0000 

From Mount Vernon, Kentucky 007."> 

From llarliniiton quarry, Rookwood, Illinois 01 14 

From Bowling Green, Keutneky 0077 

.01111 
From Bedford, Washington County, Indiana OOS.i 

Mean 0070 

Sandstones. 

Amount of 
Description. pcniinncnl 

swelling. 
Inch. 

From (romnell, Connecticut 00G7 

From Worcester quarry. East Lougmeadow, Massachusetts 0022 

From Kibbe quarry, East I.ongmeadow, Massachusetts 0020 

.ooo:i 

From Maynard quarry. East Longmeadow, Massachusetts 0010 

From Kettle River quarry. Pine County, Minnesota 0018 

From Cabin Creek quarry, Johnson County, Arkansas OOIS 

From Sebastian County, Arkansas 001.5 

From Bourbon County, Kansas, " Bandera stone " 0017 

From Piedmont quarry, Alameda County, California 0174 

From Olymiiia, Washington 003.5 

From Clnickauut, Washington 00.52 

.014S 
From Tenino, Thurston County, Washington 0035 

Mean 004 7 

(7) Tests to ascertain the fireproof qualities of stone. The expan- 
sive power of natural temperatures is but slight in comparison with 
that induced Ly the heat of a bui-ning Iniilding, which is at times so 
great that no natural material can be expected to remain uninjured. 
Several years ago H. A. Cutting ' made a small series of experiments 
to ascertain the relative powers of resistance of various stones to 
artificial temperatures. According to his results the heat resisting 
capacity of the various stones tested stands in the follo\ving order, the 

' Weekly Underwriter. 



112 THE BUILDING AND DECORATIVE STONES 

first mentioned being the least affected: (1) marble, (2) limestone, 
(3) sandstone, (4) granite, and (5) conglomerate. The tests were 
however scarcely sufficient to fully establish any such law. Prof. 
Dodge, to whose work on the Minnesota Survey reference has already 
been made, proceeded as follows: 

The prepared samples were first heated to a red heat in a muffle 
furnace, the temperature being raised gradually. Twice each sample 
was removed with tongs, and carefully inspected to note the effect of 
heating. 

After this heating test the samples, while still very hot but at a 
temperature below redness, were immersed in a tank of water for a 
few minutes. The action of the water in cavising cracking or crumb- 
ling was noted. Such tests are really too severe to be used in any 
but the most extreme cases since no stone can be expected to pass 
through such an ordeal unharmed. 



£ 



^»"^ 



Fi<:. 15. — Cube for crushing tests. 

(8) Tests to ascertain resistance to crushing. This is far the most 
common test that is applied to stone. Concerning the utility of such 
tests as usually applied, the writer has expressed himself elsewhere. 

The first systematic and really exhaustive series of these tests made 
in America were those of Q. A. Gillmore, of the Engineer Depart- 
ment, United States Army, whose results were published in the An- 
nual Report of the Chief of Engineers for 1875. 

The size of specimens operated upon by Gillmore in the systematic 
part of his work was that of a two inch cube. During his preliminary 
experiments he found that at least within certain limits the compres- 
sive resistance of cubes, per square inch of surface imder pressure 
increases in the ratio of the culiic roots of the sides of the respective 
cubes expressed in inches. Thus the actual resistance of a ^ inch 
cube, expressed per square inch, was about 6,080 pounds, while that 
of a 4 inch cube, that is one bavins' S times the length of side, was 



JIAKVLAXD GEOLOGICAL SURVFA" 113 

11,720 poTinds per square incli. The general conclusions arrived at 
was that having ascertained from an average of several careful trials 
the crushing resistance of a 1 ineli cube, an 8 inch cube of the same 
nature shouhl sliow twice ms much resistance per square inch of 
crushing surface as tlie 1 incli. This conclusion was not fully borne 
out by later experiments but enough was gained to show that for pur- 
]K)ses of fair comparison it was necessary that all tests be made on 
cubes of approximately the same size. Gillmore's tests showed also 
that mucli il('[»ends on tlie breadth when compared with the height 
of the specimens tested. Thus he found that while an inch cube 
of Berea standstone crushed imder a weight of 9500 pounds, a block 
of the same stone 1 inch thick by two inches square, and which con- 
tained therefore only four times the amount of material sustained not 
merely 4x9500 or 38,000 pounds but 70,000 pounds. When the 
height or thickness of the specimen was doubled, so as to have the 
form of a two inch cube it surtained but 50,000 pounds, and when 
the height was increased to twice that of the width, or base, it sus- 
tained only 44,000 pounds. 

Gillmore further found that there was a great difference in the 
results obtained by crushing bet\veen plates of various kinds of mater- 
ial as wood, leather, lead and steel, in every case the tests between 
steel plates yielding the highest results, a fact which was shown to 
be due to the lateral spreading action of the other substances men- 
tioned. As a result of these and other trials which need not be given 
in detail here it seems best that jiressure tests be made on two inch 
cubes, the faces of which have been carefully sawn or ground so that 
no incipient fractures ai'e developed, and those which are to come in 
contact with the steel plates rubbed with a vei-y thin coating of plaster 
of Paris to fill in all inequalities. In the process of testing it is cus- 
tomary to note (1st) the number of pounds registered by the crushing 
machine -when the stone first begins to show signs of fracture, and 
(2nd) the number registered when it actually crushes. Both of these 
phenomena are noted in the accompanying tables (p. 145, 15G, 1G4). 

The result of many experiments has been to show that most lami- 
nated or bedded rocks will bear a greater pressure in a direction at 
8 



114 THE BUILDING AND DECORATIVE STONES 

right angles to tlieir bedding than parallel thereto. That is, a block 
will stand more if laid on its natural bed than if stood on edge. This 
result may not always appear in a small series of tests owing to 
sundry imperceptible differences in the specimens tested, but it is 
nevertheless true in a general way. 

Study of the results of large numbers of tests that have been made 
at periods extending over many years have shown that the results of 
recent tests are much higher than those several years ago, even on 
the same class of material. This residt, which is simply due to the 
perfection to which the methods have been brought, is so great that 
very unfair deductions may be drawn regarding the relative strength 
of materials tested at different times under perhaps dift'erent condi- 
tions. In fact there are few things more misleading than a tabulated 
statement of crushing strengths, made at intervals covering many 
years, on cubes of varying sizes, and under conditions which are not 
stated. 

It is interesting to note the form assumed by the fragments as a 
result of crushing. 

As a rule, a perfectly homogeneous rock gives rise to conical or 
pyramidal fragments according as the stone is friable, of a pronounced 
granular structure like sandstone, or compact as are most granites. 
Stones crushed on edge naturally split up into flakes or slabs. In the 
plate herewith given (Plate VI) are shown the shape of the fragments 
formed during the tests tabulated. (See p. 113.) 

In all this work of testing the strength of stone it is well to remem- 
ber that stones as a rule are apparently weaker when saturated with 
moisture than when dry. It is true that we have not at hand to-day 
sufficient data for proving this conclusively, but such data as are at 
hand are more than merely suggestive. Thus ]\IM. Tournaire and 
Michelot have shown ' that cubes of chalk three decimeters in diameter 
crushed wet under a pressure of but 18.6 kilograms; but when air 
dried under 23.5 kilograms and when stove dried under 86.3 kilo- 
grams. Delesse's experiments on 5 centimeter cubes of chalk and the 
" ealcaire grossier " found that the chalk when wet crushed under a 
pressure of 12.9 kilograms; Avhen air dried 23.6 kilogi-ams, and when 

'American Journal of Science, 3rcl series, vol. xvi, 1S7S, p. 151. 



JIAKYLAND GEOI.OGICAI. SURVEY 



115 



stove dried 36.4 Icilogvams. The limestone (caleaire grossiei") crushed 
when wet under 24.35 kilogTanis, when air dried kilogi-ams, and 
when stove dried inider 42.7 kilogTams. Inasmuch as stones in a 
foundation are subject to periodic or perhaps constant saturation these 
facts are worthy of consideration. 

It is well to note here too that the effect of temperature changes 
upon stone is weakening. In the tests made by the Army I'^ngineers 
to which we have already referred ' it was found that samples which 
had been submitted to the hot and cold water tests to ascertain their 
coefficient of expansion and contraction had suffered to a remarkable 
degree. The average result showed that the stones from the water 
baths lost in strength on an average 34.9 per cent, the granites, after 
passing through both hot and cold water tests, poss(!ssing but 83.7 per 
cent their original strength; the marbles 46.2 per cent; the limestones 
58.8 per cent, and the sandstones 66.9 per cent. 




Viv, II). — Bar f.ir expansion tests. 



Tests on bricks made by the United States Army Engineers showed 
that the wet samples had as a rule but 85 per cent the strength of the 
dry ones, the greatest loss in strength occurring in medium hard and 
hard brick. 

(9) Tests to ascertain elasticity of stone. Tests to ascertain the 
elasticity of stone when sulijccted to compressive and transverse 
strains, have also been made by the United States Army Engineers, 
and the results obtained may well be noted briefly here, though for 
details the reader is refeiTcd to the original publications.' 

The tests of elastic properties under compression were made upon 
prisms 4-in. by 6-in. by 24-in., the loads being applied parallel to the 

• Report on Tests of Metals, etc., 1S95. 

'•' Report of the Tests of Metals, etc., made at Watertown Aisciial. Years 
1890, 1894 and 1895, Washington, T). C. 



116 



THE BUILDING AND DECOEATIVE STONES 



direction of the long sides (see Fig. 16), tlie compressibility being- 
measured by means of a micrometer. It was found here, as in the 
tests for ascertaining expansion that the stones shortly developed a 
permanent " set," from which they did not recover during the period 
of time over which the observations were extended. 

COMPRESSIVE ELASTIC TESTS. 

APPLIED LOADS. 20" IN GAUGED LENGTHS, 

Total nnunrii ^" square Compression o„, jn-i, 
'°'*' P°"°"^-inch pouudB. inch. »et men. 

Granite, Milford, Mass 31.5,460 0,000 0.0339 .001.5 

Granite, Troy, New Hampshire 343,600 10,000 .0411 

Griinite, Troy, New Hampsliire 319,340 9,000 .0S79 .0063 

Marble, Cberokee, Georgia 144,960 6,000 .0133 

Marble, Cberokee, Georgia 48,320 3,000 .0037 .0006 

Limestone, Mount Vernon, Kentucky 59,833 3,400 .0183 

Limestone, Mount Vernon, Kentucky 3,493 100 .. .0033 

Sandstone, East Long Meadow, Mass 96,400 4,000 .05.54 

Sandstone, East Long Meadow, Mass 3,410 100 . . .0136 




Fig. 17. — Bar for elasticity tests. 



The transverse tests were made on similarly prepared prisms, sup- 
ported at the ends, tlie load being applied at the middle as shown in 
Fig. 17. In the table below is given the residts of a few selected 
tests, as determined by the authorities referred to, the term modulus 
of rupture signifying the weight in pounds under which the bar 
breaks; only the maximum results are tabulated. 



MARYLAND GEOLOGICAL SDKVEV 



117 



Xo. of 
tests. 



203 



N'o. of 

teetH. 



204 
205 



TRANSVERSE TESTS. 
Pink Granite from Milford Pink Oranile Company, Boston, Jfasa. 

Dimensions. tlltlmatc strength. 



Distance between 
end supports. 

Inches. 

19 



Inches. 
4.03 



Ueptb. 

Inches. 
6.03 



Pounds. 
0,030 



Modulus of 
rupture. 

Pounds. 

1,74.5 



Granite from Pigeon Hill Granite Compani/, Hockport, Maxs. 

Dimensions. Dltimate strength. 

BreaUtli. Depth. Total. 

Inches. Inches. Pounds. Pounds, 

4.03 6.03 12,320 2,404 

4.01 6.06 13,450 3,416 



Distance between 
end supports. 

Inches. 
19 
19 



.Modulus of 
rupture. R. 




Fig. is. — Bar for shearing tests. 



(10) Tests to ascertain resistance lo shearing. The term shearinfj 
as used in geology includes a strain due not merely to pressure in one 
direction, but also those uue to pulling or thrusting in all directions 
up to those perpendicular to the first. It is a fonn of strain likely to 
be brought to bear on stone in many parts of a building, bridges, etc., 
and is by no means unimportant. As performed by the Army Engi- 
neer the test consists in subjecting prepared prisms supported at each 
end by blocks 6 inches apart, to pressure applied by means of a 
" plunger " having a face 5 inches wide, there being then a clear- 
ance space of half an inch between the sides of tlie plunger and the 
blocks on each side, below (sec Fig. 18). 



138 



THE BUILDING AND DECORiVTIVE STONES 



The results of a few experiments of this nature are given below. 
It is worthy of note that " before the shearing strength was reached 
during the tests, tension fractures were developed on the under side 
of the stone midway the 6-inch free span, and there were instances 
in which longitudinal fractures opened in the ends of the stones, cor- 
responding to shearing along the grain in the tests of timber." 



NATURAL STONES— Shearing 
Slonfx from Charles River Stone Company, 



Tests. 
Boston, Mass. 



No. of 
tests. 


Description. 


Shearing 
dimension. 




Transverse 

fracture 

developed 

on tension 

side. 


SiiearinK 
strengtli. 


Is 


Total. 


Per 

square 
inch. 

lbs. 








Indies. 


sq. in. 


lt)S. 


lbs. 




240 


Milford gmniti-, Milford, Mass 


4.02x0.03x3 


48.48 


34,.S00 


108,400 


3,230 


one 


241 


" 


4.03x0.01x3 


48.33 


37,300 


138,800 


3,872 


two 


24a 


Brauford i;ranite, Brauford, Couii 


4.04x0.01x3 


48.50 


18,900 


93,500 


1,925 


one 


243 


" 


4.03x0.01x3 


48.44 


19,600 


84,400 


1,743 


one 


244 


Troy granite, Troy, New Hainpshire. . . 


4.03x0.00x2 


48.30 


39,900 


107,900 


3,331 


one 


24.5 


(1 li .t tt it 


4.00 X 0.02x2 


48.88 


34,400 


107,400 


2,197 


one 


240 


Maynard stone, E. Long .Me.idow, Mass. 


3.99x6.01x2 


47.90 


2.5,800 


53, 700 


1,130 


one 


247 


.. 


4.03x6.00x3 


48.34 


19,900 


63,100 


1,287 


two 


248 


Worcester stone, E. Long .Meadow-, •' 


4.00x 6.00x3 


48.00 


33,900 


00,400 


1,383 


two 


249 




4.00x .5.98x3 


47.84 


30,300 


53,700 


1,103 


two 


2.50 


Klbbe stone, Ea.st Long Meadow, Mass. 


4.00 X 6.00 X 3 


48.00 


25,100 


47,600 


993 


two 


251 


1( t> a n .c 


4.00 X 6.00x3 


48.00 


39,400 


03,800 


1,308 


one 


253 


Southern marble. Marble llill, Georgia. 


4.03x6.00x3 


48.34 


30,70(1 


50,100 


1,163 


one 


253 


.c 


4.03 X 0.00x2 


48.34 


30,300 


73,400 


1,501 


one 


254 


Tuckahoe marble, Tuckalioe, New York. 


4.03x6.01x3 


48.33 


38,8.50 


7.5,100 


1,.5.54 


one 


255 


" 


4.03x0.00x3 


48.34 


3.5,700 


08,800 


1,430 


one 



No. 

of 

test;. 



NATURAL STONES.— 8IIEAUING Tests. 

PiJik Grunltt: from Mil ford Pu/k Granite Company^ Boston^ Ma»i>. 

Shearing; strength. 

Transvei'se 

Shearing 



Shearing 
dimensions. 



Inches. sq. iucli. 

362 6.01x4.02x2 48.32 



Transverse 
fracture 
developed on ten- 
sion side. 


Totiil. 


Per square inch. 


a- -a 

II 


Pounds. 


Pounds. 


Pounds. 




38,300 


88,200 


1,S25 


on 



MARYLAND GEOLOGICAL SURVEY 119 

Granite from Pigeon HiU Granite Company, Rockport, Mass. 

Sla-arlnK strength. „ 

Xn Irnnpverse ^ — , *-a 

"of' Stiearinp! Shearing fracture g£ 

test ulmensions. area. developed on ten- Total. Per square Inch. n g 

Blon side. 5.C 

m « 

Inches. sq. inch. Pounds. Pounds. Pounds. 

36.S 6.05x4.00x2 48.40 4.5,400 '.l!),10ll i,04T 

•2M 0.01x4.00x2 4S.0S 38,600 50,600 I,(l.-)2 

(11) Tests to ascertain the specific gravity. Tlip dotcrmiiiation of 
the specific gravity of a stone, or its weight when compared with an 
eqiinl volume of water, is of interest, and sometimes of practical 
iinportaiicc. Of two stones of the same mineral nature, the one hav- 
iui;- the highest specific gravity, that is the greatest weight Imlk f<ir 
hulk, will be the least alisorptive, and hence as a rule the most dura- 
ble, ^loreover the specific gravity detenuination afi'ords an easy 
method of determining the weight of any stone per cubic foot. Tlie 
weight of a cubic foot of distilled water, at a temperature of 4° C, 
is 62.5 pounds. Hence, if we find that a stone has a specific gravity 
of 2.65, that is to say is 2.65 times as heavy as water, we get its 
weight by simply multiplying 62.5 by 2.65 which gives ns 165.62, 
which is the average weight per cubic foot of granite. Specific gra-\'- 
ity tests are made by carefully weighing a small piece of the rock in 
the air, and then weighing it again in water, the weight in the last 
case of course being less. The figures representing the weight in air 
divided by those representing the loss of weight in water, give the 
specific gravity. It is customary in making the weighings to have 
the rock fragment suspended to the arm of the balance by a fine wire, 
or hair, so as permit of its being readily immersed in water fnr the 
second weighing. In very accurate determinations the vessel of 
water containing the fragment should be placed upon the bell jar of 
an air pump and the air exhausted in order to remove the air from and 
admit the water to the pores of the stone. 

The Testing of Kooiixg Sl.vtes. 

The cuuditiou of exposure under which slates on a roof are placed 
are such as to require a slight modification of the tests as above 
outlined. 

Obviously the matters of toughness and permanency of color are 



120 THE BUILDING AND DECOB.ATIVE STONES 

of greatest importance. The first is readily ascertained by direct tests 
made on the fresh slates, and on samples which have been submitted 
to the corrosive action of acids. The matter of permanence of color 
is not however so easily solved, and indeed as yet the cause of the 
fading of some of our slates is not well understood. 

The best series of tests that, so far as the writer is aware, have yet 
been inaugurated, are those of Prof. Mansfield Merriman,' from whose 
paper the facts given below are mainly derived. The tests here 
quoted were made wholly on Pennsylvania materials. Others made 
on Peach Bottom materials are quoted on pp. 228-231. 

The strength and toughness of slate, writes Prof. Merriman, are 
important elements in preventing breakage in transportation and 
liaudling, as well as in resisting the effect of hail, or of stone mali- 
ciously thrown upon the roof. They are also brought effectively into 
play by the powerful stresses produced by the freezing of water around 
and under the edges. Porosity is not a desirable property, for the 
more water absorbed the greater the amount of disintegration through 
freezing. Density tests are of value, since the gTcater the specific 
gravity of one of several similar substances, the greater is its sti-engtli. 
Hardness may or may not be a desirable quality, accordingly as it is 
related to density or to brittleness. Lastly a test for corrodibility, or 
the capacity of being disintegrated by the chemical action of smoke 
and of fumes from manufactories, is desirable. 

(1) Strength and Toughness.- — The tests were made upon selected 
pieces 12 inches wide, 24 inches long and varying from tu to ^ of an 
inch in thickness. The pieces were supported in a horizontal position, 
upon wooden knife edges 22 inches apart and the loads were applied 
upon another knife edge placed half way between the supports. This 
load being applied by means of sand running out of an orifice in a box, 
at the rate of 70 pounds per minute, the flow being checked by means 
of an electric attachment the moment rupture took place. The de- 
flection or bending of the slate in the pieces tested was sufficiently 
great to permit of easy measurement, and both the amount of bending 
— indicating toughness — and the actual strength of the slate could 

• Trans. Am. Soc. of Civil Engineers, vol. xxvii, 1892, x^P- 331-349. 



MARYLAND GKOLOGICAL SURVEY 121 

be tlms ascertained by a single test. The test of specific gravity of 
slate and the porosity are made in the same way as vdih other stone. 

(2) Corrosion by Acids. — In making these tests very dilute solu- 
tions were prepared, consisting of 98 parts water, 1 part of hydro- 
chloric acid and one part of sulphuric acid. In this solution pieces of 
slate some 3x4 inches in size wore inmiorsed for 63 hours each, after 
careful weighing. At the expiration of this time tlicy were removed, 
allowed to dry for two hours, and again weighed, the differences 
between the first and secdud weighing of course representing the 
amonut of corrosion. 

(3) Softness or Capacity to Eesist Abrasion. — This was deter- 
mined by simply holding a weighed block of slate some 4x4 inches 
against a gTindstone under a constant pressure of 10 pounds. The 
table below is given to show the mean results of the tests above 
enumerated, on certain Pennsylvania slates, as made by the authority 
quoted. The general conclusions adopted as a result of these tests 
are also given. 

MEAN RESULTS OF PHYSICAL TESTS. 

r-pmy. Measured by Z'eT ^aSf" of'tt. 

Strength Modulus of rupture, in ihhuhIs per siiuare 

inch 7,1.50 '.),S10 S,480 

Toughness.. . Ultimate deflection, in inches, on supports 

33 inches apart 0.270 0..'?l:l 0.291 

Density Specific gravity 2.77.5 2.7.S0 2.777 

Softness Weight in grains, abraded on grindstone 

under the stated conditions 80 12S 104 

Porosity Percent of water absorbed in 24 hours, 

when thoroughly dried 0.23S 0.14.5 O.IOI 

Corrodibility. Per cent of weight lost in acid solution 

in fi« hours 0..547 0.44(! 0.4n« 

Conclusions. — The above investigation seems to indicate the fol- 
lowing conclusions regarding the soft roofing slates of Xorrhnmptnn 
county, Pennsylvania: 

1. Slates containing soft ribbons are by common consent of an 
inferior quality, and should not be used in good work. 

2. The soft roofing slates weigh about 173 pouudj- per cubic foot, 



1-2 THE BUILDING AND DECORATIVE STONES 

and the best qualities have a modulus of rupture of from 7000 to 
10,000 j)ounds j)er square inch. 

3. The stronger the slate, the greater is its toughness and softness, 
and the less is its porosity and corrodibility. 

4. Softness, or liability to abrasion, does not indicate inferior roof- 
ing slate; but, on the contrary, it is an indication of streng-th and 
good weathering qualities. 

5. The strongest slate stands highest in weathering qualities, so 
that a flexural test affords an excellent idea of all its properties, par- 
ticularly if the ultimate deflection and the manner of rupture be 
noted. 

6. The strongest and best slate has the highest percentage of sili- 
cates of iron and aluminum, but is not necessarily the lowest in car- 
bonates of lime and magnesia. 

7. Chemical analyses give only imperfect conclusions regarding 
the weathering qualities of slate, and they do not satisfactorily explain 
the physical properties. 

S. Architects and engineers who write speciiications for roofing 
slate will probably olitain a more satisfactory quality if they insert 
requirements for a flexural test to be made on several specimens 
picked at random out of each lot. 

9. Although the field of this investigation is pi'obably not suffi- 
ciently extended to fully warrant the recommendation, it is suggested 
that such specifications should require roofing slates to have a modulus 
of rupture, as determined by the flexural test, greater than 7000 
pounds per square inch. 

Probably more can lie learned regarding the lasting powers of a 
slate by microscopic methods than in any other class of rocks. As 
the writer has elsewhere noted,' the roofing slates occupy a very 
interesting position in the lithologic series. Originally formed as 
a fine silt on a sea bottom, they owe their fissile properties not to 
sedimentation but to squeezing and shearing forces such as are inci- 
dental to the formation of mountain chains. But this shearing, while 
developing schistosity, or cleavage, has also brought about other 
structural modifications in the slate which, although not so manifest, 

' Trans. Am. Soc. of Civil Engineers, vol. xxxii, 1S94, p. 540. 



MARYLAND GEOLOGICAL SUBVET 123 

are nevertheless of great importance. If we examine a thin section 
of a slate under the microscope we shall find that the individual par- 
ticles of (i[uartz and feldspai", etc., of which they are composed, are 
all arranged with their longer axes parallel with each other and witli 
the direction of cleavage. In fact it is to this cause that the finely 
fissile nature of the slate is largely due. But this is not all. Pres 
sure always causes heat, and since all rocks lying in the ground con- 
tain more or less moisture, the rock becomes permeated with warm 
or hot solutions which may be productive of partial solution and 
recrystallization. In fact, our roofing slates pass by insensil)le grada- 
tions into crystalline schists. So far as the writer's experience goes, 
the greater the amount of crystallization, that is the more nearly the 
slates approach the crystalline schists in sti-ucture and composition, 
the tougher and more durable they are likely to be. It is unforttinate 
that this crystallization interferes to some extent with the fissile 
property, the slates of this nature yielding thicker slabs, and with 
less even surfaces. Such, while more desii-able, demand increased 
strength in roofing timbers. The point to be made here is, however, 
that the microscope, in showing the crystalline condition of the slate, 
the presence or absence of pyrite, or of free carbonates of lime, iron 
or magnesia, such as are likely to be corroded by rains, will enable 
one to draw some inference regarding its lasting power. A chemical 
analysis shows what the slate contains, but it does not show the form 
of combination of the various elements. 



AN ACCOUNT OF 

THE CHARACTER AND DISTRIBUTION OF 
MARYLAND BUILDING STONES 

TOGtTHl-.R WITH 

A HISTORY OF THE QUARRYING INDUSTRY 

BY 

EDWARD B. MATHEWS. 



INTRODUCTIOX. 

The rocks of the state of Maryland present many varieties of excel- 
lent building and decorative stones. The greater amount of the pro- 
duct is obtained from that portion of the state north of Washington 
and east of Harpers Ferry, W. Va., which has been termed the Pied- 
mont Plateau, and which includes some of the oldest rocks found in 
the state. The central location of this area, traversed by two main 
railroad lines and several more local ones, places it within convenient 
distance of the prominent cities and towns of the Middle Atlantic 
coast and renders the products both valuable and available wherever 
the local conditions are otherwise favorable. Counteracting the value 
of this central location, however, is the fact that the state of Mary- 
land represents but a section across a series of geological formations, 
which are present in Pennsylvania and Virginia, where there are 
offered similar opportunities for quarrying building stone. In some 
instances operations were commenced in these areas earlier than in 
Maryland, with the result that trade has been diverted to neighboring 
states, which might be gained for Maryland by more energetic and 
intelligent action on the part of the local operators. At the present 
time the operations in the area are in no wise commensurate with the 
supply of material at hand, and the demand which might be devel- 



126 A HISTOEY OF THE QUAERYING INDUSTRY 

oped if sufficient foretliouglit and care were expended to make the 
output uniformly and economically quarried. 

The rich variety in the rocks adapted to structural and decorative 
purposes renders a description of each variety out of the question, and 
it becomes necessary to treat the occm-rences under the following 
heads: I. The Granites and Gneisses. II. The Marbles, Serpen- 
tines and Limestones. III. The Qiiartzites and Sandstones. IV. 
The Slates and Flags. 

Previous Publications. 

The bibliography at the end of this chapter is the somewhat dry 
expression of the amount of study which has been carried on regard- 
ing the building stone products of the state, their geological occur- 
rence, properties and industries. From the books and papers therein 
enumerated one may glean the folloM'ing resume of the results which 
have been accomplished. 

The earliest reference of scientific value to the quarrying of Mary- 
land stone is found in a paper by H. H. Hayden (1), published in 
1811. In this very rare and interesting report we learn, that, at the 
time of writing, the stone " a mile and a half from Baltimore " (loca- 
tion of the present quarries on Jones' Falls) Avas regarded as " highly 
valuable and useful in various branches of masonry," and that it was 
" quarried on both sides of Jones' Falls, to considerable advantage to 
the proprietors." 

Eight years later the Rev. Elias Cornelius (2), after an extended 
trip through the southern states from Boston to ISTew Orleans and 
return, gave a sunnnarv cif his obser-\-ations on the mineralogy and 
the geology of the country traversed to Professor Silliman, who pub- 
lished the same in the first volume of his journal. This letter gives 
the earliest account of the " Potomac Marble " which has been found 
in any scientific journal, and furnishes information concerning the 
cost of the original columns in the old Hall of the House of Repre- 
sentatives in Washington, as well as the name of the man who first 
brought this peculiar rock into use. 

The next reference to the quarries of Maryland is found in a paper 
by Mr. William E. A. Aikin (3), who was at that time Professor of 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE VII. 




MARYLAND GKOI.OGICAT, SIKVEY 127 

Xiitnial riiilosophy and Chemistry in the iloiiiit Saint ^Mary's Col- 
lege in Emmitsbnrg. In this paper reference is made to the fact 
tliat •' the granite may be well seen in the neighborhood of Ellicott's 
Mills, where tliere are extensive quarries that furnish vast quantities 
for the Baltimore market," and the fact is noted that " at one place 
[Ijamsville?] quan-ies liave been opened and furnisli a tolcra])lc, 
coarse roofing slate." 

^fention is also made of the quarries in the " Potomac marble " 
and of many others about Frederick and Hagerstown while the author 
notes that " a few miles east of Hagerstown, the exact spot I am not 
acquainted wiili, this stratum [Shenandoah limestone] includes a bed 
of white and perfectly fine grained limestone, whicli is quarried for 
white marble, and answers well for that pin-pose." 

In Ducatel and Alexander's "' Kcport on the projected survey of 
ilaryland," publislicd in 1834 (4), there is a summary of the existing 
industries dependent on the natural resources, and a plea for greater 
information concerning them. In this summary there are brief and 
incidental references to the granites of Port Deposit and EUicott 
City; to the Seneca and Sugarloaf sandstones; to the slates of central 
Maryland; and to tjic marbles of Point of Kocks, Carroll county and 
Boonsborough. The total amount of information, however, would 
scarcely fill a page, and the references are of little more than his- 
torical value. From the date of this earliest report until 1836 the 
Geologist and Engineer were so busy with the survey and study of 
the features of eastern and southern Maryland that no reference is 
made to the structural materials of the northern tier of counties be- 
fore the publication of the " Report on the Xew Map of Maryland," 
in 1836 (5). In this paper attention is called to the sedimentary 
origin of the Baltimore gneiss, the peculiar weathering of the granites 
at Woodstock, and the probable source of the pebbles in the " Capitol 
or Potomac breccia." Succeeding reports of Ducatel and Alexander 
give a few more details in the discussion of the resources of the diifer- 
ent counties, wliicii may be found as follows: Cecil and ^lontgomery 
in the report for 1837 (6); Harford and Baltimore in that for 1838 
(7); Frederick and Carroll in that for 1S39 (S); and western Mary- 



128 A HISTOEY OF THE QUAKEYING INDUSTRY' 

land in the last for 1840 (9). The most important work on the 
building stones of the state piiblished prior to the war is found in 
a Report of the Board of Regents of the Smithsonian, presented to 
the Senate in 1849. This contains, besides many letters showing the 
price of stone and the state of the industry at that time, the following 
reports: One by Dr. Charles G. Page (10) " To the Building Com- 
mittee of the Smithsonian Institution on the action of frost upon 
certain materials for building " ; another by Mr. James Renwiek, 
Jr. (11), entitled " Report to the Building Committee of the Smith- 
sonian Institution," which deals with the quality and quantity of 
serviceable stone exposed along Seneca Creek; and two by Dr. David 
Dale Owen, entitled a " Report on the Baltimore county quarries " 
(12), and a " Report on the sandstones of the Potomac " (13). 
These give the first accounts by geologists and architects who visited 
the Maryland quarries to study their ability to supply good structural 
materials in large quantities. 

Somewhat later W. R. Johnson (15) used the facts published in the 
preceding reports, together with information furnished by Robert 
Mills and by Mr. Dougherty in his comparison of the strength and 
durability of foreign and domestic building materials. His sum- 
mary includes practically all of the pressure test results which had 
been obtained up to that time. Many discrepancies appeared which 
the author thought conformed to the law that there is " a direct rela- 
tion between the power of resistance of a cube and the product of the 
area of the hase multiplied into the cube root of that area." The law 
has not been accepted and the paper is chiefly of historical value 
through reference to papers which are now unobtainable, since many 
of the figures therein contained are not comparable with those ob- 
tained by the testing made in recent years under better conditions. 

Prof. Chas. T. Jackson (16) visited the marble quarries at Texas 
in 1859 at the reqviest of one of the operators, and on his return to 
Boston gave a brief account of the stone of the quarry visited, and 
drew comparisons between it and the stone from a neighboring quarry, 
which had been accepted for the extension of the General Post Office 
Building in Washington. The report is short, but contains figures 



MARYLAND GEOLOGICAL SURVEY 129 

representinij the specific gravity, weight per cubic foot, crushing- 
strength and clicniical composition of two dolomites and an " ahini 
stone." 

Tyson (17) was the first to give a systematic account of the materials 
grouped in this report as building stones or structural materials. This 
appeared in the appendix to his first report, entitled " Mineral re- 
sources of Maryland." The marbles are di\'ided into three classes 
with the accessory " verde antique " and " Potomac marble " while 
numerous details are given regarding the granites, sandstones, slates, 
and flags, which are found in the state. Emphasis is laid on the 
availability of the tidewater granites and upon the slates of Harford 
and Frederick counties. The total discussion, however, is not more 
than eight pages long. 

The state report of 1865 (18), prepared by a select committee of 
the legislature, gives a somewhat more extended account of the re- 
sources of the state, as then known. It represents a compilation of 
previous work rather than the results of new investigations in the 
area. It is based in great measiire on the work of Tyson. 

Professor Genth's (20) report on the Broad Creek (Harford county) 
serpentine, published in 1875, is perhaps the first special report calling 
attention to the availability of that stone for stmctural and decora- 
tive pTirposes. Although the geological interpretation of the area is 
open to question the paper remains of value from its descriptions of 
the stone and the chemical analyses therein presented. 

The well known " Report on the Compression Strength, Specific 
Gravity, and ratio of Absorption of the Building Stones in the United 
States" by Lieut. Q. A. Gillmore (21) deals almost entirely with the 
material from areas outside of Maryland, but docs include the results 
of tests on Port Deposit granite. 

Since the publication of the preceding report by Gillmore, the 
work, which has been done on the building stones of the state, has 
been conducted almost entirely by the Tenth Census Commission, 
the U. S. Geological Survey and the Johns Hopkins University. The 
report by the Census Commission includes many statistics (23) indi- 
cating the state of the industry in 1880, a " Description of the Quar- 

9 



130 A HISTORY or THE QUAKKYING INDUSTRY' 

ries and Quarry Kegions compiled from notes of Messrs. Huntington, 
Monroe and Singleton " (24) and notes on the building stones used 
in Washington by Geo. P. Merrill (25). The last paper gives many 
dates at which Maryland material was used in the construction or ex- 
tension of the Government buildings. 

Somewhat later Merrill (26) published a handbook on " The Col- 
lection of building and ornamental stones in the U. S. ]S!"ational Mu- 
seum," which had accumulated from the Centennial Exposition at 
Philadelphia in 1876 and from the Tenth Census collections of 1880. 
This book shows that about fifty specimens of the collection came 
from Maryland, and, that they represent many of the varieties which 
are described in the succeeding portion of this report. The author 
gives short summaries of the occurrence and character of these rocks 
under their proper headings. The work of the U. S. Geological 
Survey has been twofold, statistical and areal. The former has been 
conducted from Washington, and has led since 1883 to yearly state- 
ments concerning the output and state of various industries during 
the preceding year. This work has been carried on to a greater or 
less extent in co-operation with the Johns Hopkins University, and has 
led to a series of papers by Williams, Hobbs, Keyes, Grimsley and 
others, who have been occupied largely vsdth the more purely scien- 
tific aspects of the problems. Williams' (27, 39) work deals particu- 
larly with the broader geological problems; Hobbs' published papers 
include detailed discussions of certain of the granites and gneisses in 
the vicinity of Baltimore; Keyes' shorter papers (31, 32) deal with 
the weathering and petrographical features of the granites, while his 
longer paper on the same subject gives more of economic interest. 
Grimsley's (35) publications on the granites of Cecil county deal par- 
ticularly with the Port Deposit rock, and give many suggestions re- 
garding the geology and economic features of the northwestern part 
of the county. Altliough all of these papers arc devoted especially to 
the purely scientific questions, one may find many incidental refer- 
ences to the economic products, which have increased considerably 
the present stock of information. 

Two works of later date deserve especial notice, viz., Keith's " Ge- 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE VIII. 




tM^^^^mik 



KOLIATED GR.^.MTE. 
rORT DEPOSIT. CKCU- COINTY. 



MARYLAND GEOLOGICAI, SURVEY 131 

ology of the Catoetin Bolt " (36) and " Maryland, its Kesources, In- 
dustries and Institutions " (32, 33). The first gives the most exhaus- 
tive discussion of the formations of Frederick and Washington counties 
which has been published and furnishes many facts on the character 
and occurrence of the sandstones and breccias of the Newark forma- 
tion, especially of those in the vicinity of Point of Eocks. The second, 
prepared by Williams and Clark and published under the direction 
of the World's Fair Commission, presents the facts more fully and 
more attractively tlian had been attempted previoiisly. 

Soon after the inauguration of the present organization an exten- 
sive reconnoissance was made of the resources of the entire state, and 
the results of this work were incorporated within an outline of our 
present knowledge of the physical features of Maryland, which ap- 
peared as Part III of volume one of the Siirvey reports. In this 
review are brought together concisely the more important facts re- 
garding the building stones of the state, and an outline of the 
proposed investigation which has resulted in the present paper. 

From the foregoing summary of the previovisly published literature 
it is evident that many men have written on those rocks of Maryland, 
which now serve as sources for structural materials. The amount of 
matter written, however, is small, and much of that extant possesses 
only an historical interest. Since the total volume of published in- 
formation is small, and especially since many of the papers just enu- 
merated are either out of print or generally inaccessible, it has been 
deemed best to incorporate the results obtained in the presentation 
of the new facts which have been acquired by the personal inspection 
of almost every quarry found within the state. 

Bibliography. 

1. Hatden, H. 11. [" Mineralogical and Geological Description of 
the Country surrounding Baltimore to the extent of about nine miles.") 

Bait. Med. Phil. Lye, vol. 1, 1810, pp. 255-271. 

2. Cornelius, Elias. On the Geology, Mineralogy, Scenery and Cu- 
riosities of Virginia, Tennessee and the Alabama and Mississippi Terri- 
tories, etc., with miscellaneous remarks in a letter to the editor. 

Amer. Jour. Sci., vol. i, 1819, pp. 21-1-220. 



132 A HISTORY OF THE QUARRYING INDUSTRY 

3. AiKiN, William E. A. Some notices of the Geology of the Coun- 
try between Baltimore and the Ohio River, with a section illustrating 
the superposition of the rocks. 

Amer. Jour. Sei., vol. xxvi, 1834, pp. 219-232, plate. 

4. DucATEL, J. T., and Alexander, J. H. Report on the Projected 
Survey of the State of Maryland, pursuant to a resolution of the Gen- 
eral Assembly. 8vo. 39 pp. Map. Annapolis, 1834. 

Md. House of Delegates, Dec. Sess., 1833, 8vo., 39 pp. 
Another edition, Annapolis, 1834, 8vo., 58 pp., and map. 
Another edition, Annapolis, 1834, 8vo., 43 pp., and folded table. 
(Abst.) Amer. Jour. Sci., vol. xxvii, 1835, pp. 1-38. 

5. Report on the New Map of Maryland, 1836. 8vo. 104 

pp. and 5 maps. [Annapolis, 1837.] 

Md. House of Delegates, Dec. Sess., 1836. 
Another edition, 117 pp. 

6. DucATEL, J. T. Annual Report of the Geologist of Maryland. 
1837. 8vo. 39, 1 pp. and 2 maps. [Annapolis, 1838.] 

Md. House of Delegates, Dec. Sess., 1837. 

7. Annual Report of the Geologist of Maryland, 1838. 8vo, 

33 pp., map and illustrations. [Annapolis, 1839.] 

Md. House of Delegates, Dec. Sess., 1838. 

8. Annual Report of the Geologist of Maryland, 1839. 8vo. 

45 pp. [Annapolis, 1840.] 

Md. House of Delegates, Dec. Sess., 1839. 

9. Annual Report of the Geologist of Maryland, 1840. 8vo. 

46 pp., map and sections. [Annapolis, 1840.] 

Another edition, 8vo., 59 pp. and 3 plates; also Md. House of Delegates, 
Dec. Sess., 1840, n. d., Svo., 43 pp., 3 plates. 

10. Page, Chas. G. To the Building Committee of the Smithsonian 
Institution on the action of frost upon certain materials for building 
according to the Brard process. In Report of the Board of Regents of 
the Smithsonian Institution. 

Sen. Doc. 30th Congress, 1st Session. No. 23, pp. 20-22. 

11. Renv?ick, Jas., Jb. Report to the Building Committee of the 
Smithsonian Institution. 

The same, pp. 105-107. 



MAEYLAND GEOLOGICAL SURVEY 133 

12. Owen, David Dale. Ecport on tlie Baltimore county quarries. 
The same, pp. 25-32. 

13. Eeport on the sandstones of the Potomac. 

Tht" .same, pp. 36-39. 

14. Owen, Robert Dale. Hints on Public Architecture, containing 
among other illustrations views and plans of the Smithsonian Institution; 
together with an appendix relative to building materials. 1849. 4to. 
pp. 140-]99. Woodcuts, 15 plates. (No. P.) 

15. Johnson, W. E. A Comparison of Experiments on American and 
Foreign Building stones to determine their relative strength and dura- 
bility. 

Amer. Jour. Sci., 2nd ser., vol. xi, 1S.51, pp. 1-17. 

16. Jackson, Chas. T. Maryland JIarbles and Iron Ores. 
Proc. Boston See. Nat. Hist., vol. vi, 18.')9, pp. 243-245. 

17. Tyson, Philip T. Second Report of Philip T. Tyson, State Ag- 
ricultural Chemist, to the House of Delegates of Maryland, Jan. 1862. 
8vo. 92 pp. Annapolis, 1862. 

Md. Sen. Doc. [F.]. 

18. Anon. Report of the Select Committee appointed to prepare a 
statement in Relation to the Resources of Maryland. Annapolis, 1865. 
8vo. 52 pp. 

Md. House Jour, and Doc, 1865 [EE]. 

19. Anon. Description of the Property of the Maryland Marble Com- 
pany of Baltimore. Baltimore: Cushing & Medairy, 1866. 16mo. 
15 pp. 

20. Genth, F. a. Geological Report of the Maryland " Verde An- 
tique " Marble and other Minerals on the Lands of the Havre Iron Co., 
in Harford county, Maryland. Univ. of Penn., 18T5, 9 pp. 

21. GiLLMOHE, Q. A. Report on the Compression Strength, Specific 
Gravity, and ratio of Absorption of the Building stones in the United 
States. 

Kept. Chief of Engineers U. S. Army, part ii, appendix II, pp. 819-851. 
Same separately, 8vo., 37 pp., New York, Van Nostrand, 1876. 

22. BuRNHAM, S. M. History and Uses of Limestones and Marbles. 
8vo. 111., 392 pp. Boston, 1883. 

Maryland, pp. 57-58. 



134 A HISTOEY OF THE QUARRYING INDUSTRY 

23. Spencer, F. W., and Kelly, Thos. C. Statistics of Building 
Stones. 

Tenth Census, vol. x, Washington, 1884, pp. 45-105 of Report on Building 
Stones. 

Maryland references, ijp. 4r), 48, 50, 74-75. 

24. Huntington. J. II., Monroe, Chas. E., Singleton, H. K. De- 
scriptions of Quarries and Quarry Eegions compiled from notes of 
Messrs. Huntingtou, Monroe and Singleton. 

Tenth Census, vol. x, Washington, 1884, pp. 175-179. 

25. Merrill, Geo. P. (Notes on the -Building Stones of Washing- 
ton, D. C.) 

Tenth Census, vol. x, Washington, 1884, p. 357. 

26. The Collection of Building and Ornamental Stones in 

the U. S. National Museum. 

Smithsonian Kept., 1886, pt. ii, 1859, pp. 277-648, plates 1-9. 

27. Williams, G. H. Petrography and Structure of the Piedmont 
Plateau in Maryland. 

Bull. Geol. See. Aiuer., vol. ii, 1891, pp. 301-318, plate xii. 

28. HoBBS, William H. On the rocks occurring in the neighborhood 
of Ilchester, Howard county, Maryland; being a detailed study of the 
area comprised in .sheet No. IG of the Johns Hoi^kins University map. 

Johns Hopkins Univ. Cir. No. 65, vol. vii, 1888, pp. 69-70. 

29. On the Paragenesis of the AUanite and Epidote as Rock- 
forming Minerals. 

Amer. Jour. Sci., ord ser., vol. x.xxviii, 1889, pp. 225-228. 
(Abst.) Amer. Nat., vol. xxiii, p. 721. 

30. ScHARF, J. Thomas. The natural resources and advantages of 
Maryland; being a complete description of all of the counties of the 
State and City of Baltimore. Annapolis, 1892. 

31. Keyes, C. E. Some Maryland Granites and tlieir Origin. (Head 
Dec., 1892.) 

Bull. Geol. Soc. Amer., vol. iv, 1893, pp. 299-304, plate x. 

32. Williams, G. H. Mines and Minerals [of Maryland]. 
Maryland, its Resources, Industries and Institutions. Baltimore, 1893, 

pp. 89-153. 



MAE\XAND GEOLOGICAL SURVEV 135 

33. Williams, G. H., and Clark, W. B. Geology [of MarylandJ. 
Maryland, its Resources, Industries and Institutions. Baltimore, 1893, 
pp. 55-89. 

3-i. Williams, G. H. Marbles of Cockeysvillo, Md. [Quoted in Hop- 
kins, T. C. Marbles and other Limestones.] 

An. Kept. Geol. Surv. Ark., vol. iv, 1890. Little Rock, 1893, pp. 178-9. 

35. Grimsley, G. p. Granite of Cecil county in Xortlica-^tern Mary- 
land. 

Jour. Cincinnati Soc. Nat. Hist., vol. xvii, 1891. pp. 56-67, 87-114. 

'M>. Keith, Arthur. Geology of the Catoctin Belt. 
14th Ann. Rept. U. S. Geol. Surv., 1892-93, Washington, 1894, part ii, pp. 
285-395, maps and plates. 

House Exec. Doc, 5:ird Cong-., 2ud Sess., vol. .wii, p. 285. 
(Rev.) Science, n. s., vol. ii, 1895, p. 97. 

37. Keyes, C. R. The Origin and Relations of Central Maryland 
Graniles (with an introduction by G. H. Williams). 

15th Ann. Rept. U. S. Geol. Surv., 1893-94, Washington, 1895, pp. 685-740, 
with 21 plates. 

38. Secular Decay of Granite Rocks. 

Proc. Iowa Acad. Soi., vol. ii, Des Moines, 1895, pp. 27-31. 

39. Acidic Eruptives of Northeastern Maryland. 

.\mer. Geol., vol. xv, 1S95, pp. 39-46. 

10. Williams, G. II. The general relations of the Granitic Rocks in 
the Middle Atlantic Piedmont Plateau (introduction to Keyes' " Origin 
of Central Maryland Granites "). 

15th Ann. Rept. U. S. Geol. Surv., 1893-94, Washing-ton, 1895, pp. 657-684, 
with jilates. 

41. Keyes. C. R. Central Maryland Granites. 

stone, vol. xiii, ISOG, pp. 421-428 seq. 

42. Maryland Geological Survey. Wm. Bullock Clark, State 
Geologist. 

Reports, vol. i, Baltimore, 1897, 539 pp., plates 17. 

43. Merrill, George P. Rocks, Rock Weathering and Soils. 
Macralllan, New York, 1S97, 411 pp., plates 25. 



136 A HISTOEY OF THE QUARRYING INDUSTRY 



THE QUARRIES OF MARYLAND. 

Granites and Gneisses. 

Granite is the broad family name that is applied to a large and 
common group of rocks, which are usually of a somewhat mottled 
light gray color, and almost always carry two minerals, quartz and 
feldspar, as essential constituents. Besides these, which make up the 
mass of the rock, there are dark colored iron-bearing minerals, such 
as black mica, or biotite, hornblende and occasionally pyroxene. Each 
of these may be evident to the eye without the aid of a lens. The 
microscope shows in addition many other minerals such as zircon, 
apatite or epidote which are of scientific interest, but of little eco- 
nomic importance as constituents of building stones, since they influ- 
ence neither the appearance nor the wearing qualities of the material. 

The foregoing minerals usually form irregular aggregates, in which 
the individual grains interlock in such a way that the cohesive 
strength of granite is relatively high. The constituent grains vary 
very widely in size, from individuals two or more inches in diameter 
to those which are scarcely separable with the unaided eye. The ar- 
rangement of the different mineral grains is irregular and without any 
prominent lines of distribution, when the granites are unmodified pro- 
ducts of crystallization from a molten state. Subsequent action on 
the rock, however, through pressure or recrystallization, generally 
arranges the constituent minerals in some regular order, such as in 
parallel or wavy interlocking lines. It is in this way that many so- 
called gneisses or granite gneisses originate from granites, as at Port 
Deposit. True gneisses, however, usually result from the recrystalli- 
zation of rocks laid down under water, and still retain their banded 
character. Since in the trade granites and gneisses compete for the 
same work, and since, when well sorted, there is little difference in 
their practicability for building purposes, they will be treated together 
in the present chapter, the differences between the two being shown 
in the order of grouping in the discussion of the principal quarries. 



MAKVLAND GEOLOGICAL SURVEY 137 



GEOLOGIC OCCURRENCE. 



The granites and gneisses of Maryland are almost entirely limited 
to that portion of the state which has been described, in previous pai-ts 
of this paper, nnder the title of the Piedmont Plateau, an area wlii('h 
consists of masses of ancient crystalline and ])artially crystalline rocks, 
which are of both igneous and sedimentary origin. These rocks since 
their formation have been subjected to many changes and alterations, 
which have produced a marked foliation or schistosity, showing a 
general trend from the northeast to southwest, with a moderate dip 
or inclination toward the northwest. The topography of this area is 
that of a moderately high and level plateau, which has been deeply 
eroded into a series of rounded hills and valleys by the streams that 
flow across it. The granites and gneisses of the platcaii show no 
marked topographic features, although they are more prominent than 
the less resistant limestones, which occur scattered over the region. 
The industry based on the quarrying of the granites and gneisses is 
limited to a triangular area bounded on the east by the gravels and 
clays of the Coastal Plain and on the west by the less crystalline rocks 
(in the western slopes of Parr's Ridge. Within this limited area there 
are included other crystalline rocks such as the serpentines, gabbros 
and peridotites, and in a few instances certain partially metamor- 
phosed sedimentary rocks, such as the phyllites and roofing slates of 
Harford and Baltimore counties. 

The complex geological structure of the Piedmont zone plainly 
shows that the rocks have been greatly disturbed at varioiis times 
both prior and subsequent to the early base leveling of the region, 
when the crystalline rocks formed the foundations iipon which the 
more westerly sediments were laid down. Some of the elastics be- 
came involved and infolded with the massives during the process of 
many foldings, and both were then subjected to the more or less in- 
tense dynamic action of the later orographic disturbances. The in- 
fluence of the numerous intrusives, which are known to have broken 
through at variotis periods, operated still further to obliterate the 
original character of the rocks. The exact sequence of events has not 
been deciphered, altlmugh one speaking broadly may say that the 
gabbroic and dioritic types were the earliest to be extensively intruded. 



138 A HISTORY OF THE QUAREYING INDUSTRY 

These in turn were followed by the more basic non-feldspathic rocks, 
and then at different inteiwals the granite types appeared, breaking 
through all of the preceding series. 

These granites as shown by the accompanying map (Plate VII) 
occupy several distinct areas along the eastern slope of the Piedmont 
Platean. The largest of these is that extending from Sykesville to 
Washington, while the most important economically is the lenticular 
mass extending from Rising Sun through Port Deposit to the western 
side of the Susquehanna river. In all there are some fifteen areas 
where granite is prominently developed, and in at least five of these 
there are quarries of considerable economic importance. 

DISCUSSION OF INDIVIDUAL QUARRY AREAS. 
GRANITE. 

Port Deposit. 

The Maryland granite which is perhaps best known outside of the 
limits of the state is that quarried in the vicinity of Port Deposit. 
This town is situated on the Susquehanna river three miles above its 
mouth at Havre de Grace. It is one of the principal towns of Cecil 
county and has good railroad connections with Philadelphia, sixty- 
seven miles distant, Baltimore, forty-three miles, Washington, eighty- 
three miles and ITarrisburg, sixty-five miles. It is possible also for 
light crafts to ascend the Susquehanna as far as the town and receive 
their loads directly from the quarry, thus furnishing water connections 
between the quarries and Philadcdphia eighty miles, Baltimore fifty 
miles, Washington two hundred and twenty-five miles and Richmond 
three hundred miles. The gorge of the Susquehanna is emphasized 
by the wall-like mass of granite which skirts the river, from which it 
is generally separated by a narrow belt of meadow or marsh land. 
A mile above Port Deposit this rock wall becomes nearly perpendicu- 
lar, and approaches close to the river. It was this protruding mass 
of the wall which first called attention to the valuable granites of the 
area, and it is at this point that the largest quarries are operated, the 
openings extending nearly to the water's edge. While some small 
quarrying has taken place in se^-eral spots, to gain room for buildings. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE IX. 




Vir. 1 I'lIOidMlCHOGUAl'll UK r.Ii.W iri']. I'diri' IIKl'dSrr. (M.\i:xii-ii:i]Ti:x DiAMKTKUri.) 




Fu:. •.'.— ril()T(i.\nCIi(H;i{.M'II ok (;H.\.\1 TK. i:i.I,li:(irr cnv. (.Macmi-modTkn Diamk-iki!.-;.) 



MARYLAND GEOLOGICAL SURVEY 139 

the industry at present is limited to the northern edge of the town, 
where the rock now stands exposed in an almost vertical wall measur- 
ing from the base to the top something over a hundred feet. 

The value of the granites of this area was early recognized, and 
the rock was used by the settlers for the foundation of some of the 
oldest colonial dwellings. The industry arising from the quarrying 
of the rock is, however, of somewhat later origin. In the years 1816- 
1817 a bridge was built across the Susquehanna river at Port De- 
posit by the Port Deposit Bridge Company. During the process of 
construction the abutments for the eastern approach were made from 
stone quarried at the eastern end of the bridge, which is within the 
present corporate limits of the town of Port Deposit and not far from 
the site of McC'lanahan's quarries. For about ten years the opening 
so made was worked in a small way by Simon Freeze, who had sup- 
plied the materials used in the construction of the bridge. In 1829 
the owners of the Maryland canal became interested in the quarry, 
and increased its workings. In 1830 the business passed into the 
hands of Samuel Megredy and Cornelius Smith, who still farther 
increased the scope and operations, and developed a considerable trade 
witli Baltimore and other coastwise towns. Two years later Ebenezer 
D. ilcClanahan became interested in the granite quarrying industry 
through his brother-in-law Daniel ilegredy, who was then a success- 
ful operator. McClanahan became the dominant factor in the local 
development and gradiially increased the l>usincss until in 1837, 
from data furnished by Anthony Smith, Ducatel ' estimated the 
annual output at from 12,000 to 1.5,000 perches. On the retirement 
of E. D. JfcClanahan the business was transferred to his sons, who 
are at present the principal owners in the Port Deposit company, 
which controls the local industry. 

The quarries at Port Deposit, as shown by Grimsley in his work 
on the gTanites of Cecil county, are in rocks of igneous origin, which 
have been variously modified by severe dynamic action. This has 
produced a certain degree of sehistosity which causes the Port Deposit 
granites to be taken at times for a gneiss rather than a granite. This 
foliation which is produced by the parallel arrangement of the black 

' .\iiii. Kept, of the State Geolog'ist of Marvlaiid. ISliT. p. 15. 



140 A HISTORY OF THE QUARRYING INDUSTRY 

inica flakes has a northeasterly trend nearly at right angles to the 
course of the river and a dip that is almost vertical. There is no 
marked banding in the rock, but the whole face of the quarry, which 
shows thousands of feet of siu-face, appears perfectly homogeneous, 
as though made up of a single rock. Through this mass there now 
pass several series of intersecting joints of which the most prominent 
approximately coincides with the northeast trend of the foliation, but 
which inclines somewhat to the dip of the foliation. A second set 
of joints runs almost normal to the first and is almost as sharp as 
those of the main series. A third set trending west of north is in- 
clined 60° to the principal joints, while a fourth set, approximately 
horizontal, serves as bedding joints. The surface of the jointing 
plane is usually quite smooth and even, but the direction and distance 
between the parallel surfaces is not always constant. This produces 
a slight wedging in the blocks, which increases somewhat the cost of 
quarrying. On the other hand the smoothness of the joint surface 
frequently renders the rock ready for use in building without tlie 
intervention of the stone cutter, and allows the extraction of enor- 
mous nearly rectangular blocks. The expense of preparing the rock 
for use in the wall is accordingly reduced. 

Although there are some half dozen series of jointing the rock a 
short distance below the surface is very compact, homogeneous, and 
strong, as is shown by the pressure tests of Gilhnore, who found that 
the compressive strength of this rock was 13,100 pounds per square 
inch when tested '' on edge," and still more clearly by the more re- 
cent tests just completed which show a crushing strength of over 
80,000 pounds on two inch cubes. The incipient jointing planes, 
although so closely welded together as to show tliis great strength, 
are made use of by the quarrymen in trimming the huge monoliths 
and in cutting the smaller Belgian paving blocks, as the rock may be 
readily opened by means of wedge and " feathers." 

The distance between the major joints, which varies from half an 
inch to several feet, is sufficiently great to allow the extraction of 
any sized block, which can be handled advantageously by the ma- 
cldnery and by the transporting agencies. It is usually considered 



^rAI!Y^,A^•I) geological svuvey 141 

tliat the rock of the Port Deposit quarries is somewhat more easily 
worked than that at Frenchtown, which otherwise is indistinguish- 
able. This difference in working arises in part no doubt from the 
greater age, better facilities for quarrying and handling and also from 
the more convenient position of dominant lines of working in the 
Port Deposit quarries. 

The textvre of the Port Deposit granite, or granite-gneiss is highly 
characteristic. The rock is composed of the usual granitic constitu- 
ents, quartz, potassium, and lime-soda feldspai-s, l)iotite and accessory 
minerals. The most noticeable feature of the rock is the secondary 
gneissic structure, which is brought out by the arrangement of the 
shreds and flakes of black mica. This arrangement, which is better 
shown in the ledge and the hand sjipcimen ( IMate VIII) than in a tliin 
section, is seen on examination to b(> due to small disconnected gi'oups 
of mica flakes, which lie in approximately parallel lines. These lines 
are not straight or continuous, but are wavy and the flakes are dis- 
seminated or overlapping in such a way as to produce the well-known 
lenticular effect of gneiss. The color of the rock is a light bluish 
gray, which in buildings gives a bright fresh appearance at first and 
then gi-ndually becomes somewhat darker through an accumulation of 
the diist and dirt in the atmosphere. Sucli a darkening of the rock 
produces a mellowed pleasing effect in structures situated in most of 
the cities. The roughness of the surface, however, and the abundance 
of the black mica render the appearance of the older buildings con- 
structed from this rock somewhat sombre, if the atmosphere is 
strongly charged with dust j)articles. This is particidarly true in 
cities where soft coal is used extensively without smoke consumers. 
On the whole the appearance of this rock is unusually pleasing. The 
effect in a building is somewhat variable according as the rock is laid 
(m its bed or on its edge. The color on edge seems to be slightly 
brighter and more pleasing than when the stone is cut to lie parallel 
to the lamination. 

The chemical cotnposUion of the Port Deposit " granite," as shown 
in the following analysis ' of the specimen from McClanahan's quarry, 
is not normal for a granite. It is high in soda and lime and too low 

' Made by Wm. Bromwell and g-iven by Grimsley. Op. cit. p. 312. 



142 A HISTORY OF THE QUAERYING INDUSTRY' 

in potash, and the excess of soda over potash shows that the rock is 
really a quartz mica diorite rather than a true granite. Since the 
amount of potassium feldspar is greater in many of tire slides from 
other portions of the area, and since the rock is widely known as 
granite, this term is used in the present discussion in the trade-sense, 
rather than with the stricter scientific limitation. 

Analysis of Port Deponit Oranifc. 

SiO^ 73.69 

AljOj 13.89 

Fe„03 1.02 

FeO . 3.58 

CaO 3.74 

MgO .50 

Na,0 3.81 

K^O : 1.48 

H^O 1. 06 

Total Oil. 74 

From the above analysis, the results of mechanical separations by 
specific gravity, and estimates based on a study of thin slices, Grimsley 
has calculated the proportionate mineralogical composition of the 
rock. The following percentages are thought to be representative: 

Calculated percentajies, from chemical Percentajies obtained bj- speciilc gravity 

analyses. separation. 

Quartz 40.0 Sp. gr. 

Orthodase 9.0 3.6.5 (Quartz) 40.0 

Albite molecules 35.8 3.5.5-3.04 ( p^i^i 45 q 

Anorthite l.'3.6 3.67-3.8 ) 

Biotite 9,7 | Biotite, 1 ,„„ 

T. .J ^ ., „ Above 3.8-,^ ... 15.0 

Epidote 0.9 I Epulote, t 

A microscopic study of sections from the Port Deposit granite 
shows the presence of the usual granitic minerals, such as quartz, 
feldspar, dark and light micas, apatite, zircon, sphene, allanite, epidote, 
chlorite, hornblende, magnetite, garnets and occasionally calcite. The 
quartz is in relatively large sized areas, ranging from 0.5 mm. x 1.5 
mm. to 3 mm. x 5 mm. With the aid of the microscope these area.-! 
are seen to be not single units, but composed of a great number of 
small quartz fragments, which have resulted from the crushing and 
recrystallization of the original granite during the period when the 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE X. 




•J 



3 



MARYLAND GEOLOGICAL SURVEY 143 

rock received its present schistose structure. These smaller quartz 
fragments are aggregated together by intricat<> interlocking sutures 
in a way which renders the rock less rigid and at the same time capable 
of withstanding fully as much pressure as an individual grain. The 
interstitial areas between the fragments of the coarser mosaic are 
filled with a mosaic of still smaller grains. Occasionally the quartz 
shows small inclusions of iron oxide, dust-like particles and " quartz 
needles," although it usually appears exceptionally free from them. 
After a study of several sections from tlic Mc( 'lanahan quarry the 
present writer is inclined to think that the estimated proportion of 
tlie alkaline and plagioclase feldspar may better represent the char- 
acter of the rock of the area, and that the figures obtained from the 
analysis and the slides indicate a greater amount of the more soluble 
plagioclase feldspar than the average run of the quarry. If the in- 
ference is correct the stone is stronger in its resistance to decompo- 
sition than the above analysis wo\ild indicate. The feldspars, like 
the quartz, occupy well defined areas and show the shattering and 
recrystallization into a mosaic, as a result of the dynamic forces which 
have modified the rock. These mosaics arc much less frequent in the 
feldspars than in the quartz. The biotite occurs in aggTegates of fine 
shreds, showing varying degrees of orientation, and is frequently asso- 
ciated with irregadar grains or small crystals of epidote, sphene and 
allanite. The shreds and flakes are so small and so interlocked with 
minute gTains of quartz, that they offer little increase to the weakness 
due to schistosity. The other constituents are so insignificant in 
quantity and so stable under atmospheric conditions that they do not 
influence appreciably the physical or chemical stability of the rock. 

In any discussion or consideration of Iniilding stones, in order to 
appreciate the practicability of the rocks for large and permanent 
structures, it is necessaiy to know something of their physical proper- 
ties. Among these the most important, as already shown in the pre- 
vious chapter, are specific gravity, the ratio of absorption, tlic efi'ect 
of freezing and thawing, and the compression strength. The specific 
gravity must be known in order to compute the weight to each CTibic 
foot of the rock, which in turn indicates the amount of pressure im- 



144 A HISTOEY OF THE QUAEEYIXG INDUSTET 

posed on the lower courses of the structure. Since almost all building- 
stones are exposed to the atmospheric agents which influence them, 
it is well to know also what the varying conditions of temperature 
have upon a given stone. For example heating, due to the rays of 
the sun, causes the minerals to expand. Since the rate of such expan- 
sion is different for different minerals and even for different directions 
in the same mineral, there is unequal enlargement of the grains, and 
hence a loss in the cohesive strength of the rock. Other things being 
equal this change is greater in aggregates composed of many and 
vari-colored constituents. Again, if the rock is porous, the expansion 
of included moisture may rend the rock in freezing weather, so that 
it becomes necessary to know the amount of moisture absorbed by the 
rock, and so liable to expansion through frost action. The values 
obtained by Gillmore ' on Port Deposit granite are as follows: 



Position. Cracked. 


strength 

of 

spec. 


Strength 

per 

sq. in. 


Sp. Kr. 


SVeieht 

oF 1 

cubic 

tt. 


Ratio 

o( 
absorp- 
tion. Remarlcs. 


On bed 


79,000 


19,7.50 


3. 730 


170 


Coarse, strongly dashed with black. 


On edge. 33,000 


.53,400 


13.100 


3.730 


170 


do. 


On bed 


66,000 


16, .500 


3. 730 


170 


do. 


" " 


60,000 


15,000 


3-. 730 


170 


Burst suddenly. 



In the tests made during the search for a stone suitable to be used 
in the building of the Smithsonian Institution at Washington several 
Maryland building stones were studied, among which was included 
the Port Deposit granite. Dr. Chas. G. Page,' in his report on the 
action of frost on certain materials for building, gives as the specific 
gravity for the Port Dei^osit the figures 2.G0d, and as the loss by frost 
in grains 5.05. The method of investigation was the so-called Brard 
process, which consists in substituting the crystallization of sulphate 
of soda for the freezing of water. 

The tests made " for the present paper are even more creditable to 

'Gillmore, Keports on the Compressive Strength, Specific Gravity and 
Ratio of Absorption of the Building Stones in the United States. Kept, of 
the Chief of Engineers for 1875, Appendix II, p. S47. Also Republished 8vo. 
37 pp. Van Nostrand, New York, 1876. 

■ See Bibliography No. 10. 

^ The conduction of this test vfas confided to Mr. Louis K. Shellenberger, 
Engineer of Tests, for Eiehle Bi-os. of Philadelphia, who rank high as 
specialists in the construction of testing machinery. 



MARYLAND GEOLOGICAL SURVEY 145 

tlie rock. The specimens submitted were two inch cubes, carefully 
prepared and subjected to tests under the most uuiforui conditions. 
The results are as follows: 

simple Crushing. Absorption. Freezing. Crushing after freezing. 

. percentage percentage . , 

Crack. Break. of gain. ofloss. Crack. Break. 

07,1(10 0.2.io 0.0(10 83,000 86,000 

7!),:iOO 0. ID.'i 0.0 II TS.lOO 00,800 

^... «fi,200 

101,540 

Tests made by Messrs. Booth, Garrett, and IJhiir, uf I'hiladelphia, 
on a 2-inch cube gave the crushing strength as 84,730 pounds for 
2-inch cubes, which is equivalent to 21,180 pounds per .square inch.' 

The results of these various investigations clearly show that the 
Port Deposit rock is strong enough to withstand all the demands made 
upon it by the pressure of superimposed stone work in structures, 
and to resist the various deteriorating influences of frost and atmos- 
phere. 

This view of the durability of the Port Deposit granite is well sus- 
tained by a study of its mineralogical and chemical composition, and 
the evidence of disintegration shown in the quarries and in old struc- 
tures. The mineralogical composition indicates stability, as no min- 
eral is present more liable to alteration than the lime-soda feldspar, 
which itself is not particularly prone to decomposition, although the 
first of the prominent constituents to yield to atmospheric action. In- 
vestigation at the quarries, where a considerable depth of decomposed 
rock is seen to overlie the more marketable material suggests the sus- 
picion, that the Port- Deposit granite ■nail not withstand atmospheric 
agencies for any great period of time. This deceptive appearance 
arises from the fact that the crystalline rocks southward from Phila- 
delphia have not been scoured and cleaned by the action of glacial 
ice as in more northern latitudes. Thus the overlying waste repre- 
sents the decomposed products of several geological epochs, perhaps 
reaching back as far as Cretaceous time. 

The number of quarries about Port Deposit has never been very 
large, although now and then attempts have been made to establish 

' ISth Ann. Kept. U. S. Geol. Surv.. pt. \'. ISOT. p. 0(54. 
10 



146 A HISTORY OF THE QUAEEYING INDUSTRY 

rivals to the large quarries which are at present operated by the Mc- 
Clanahan & Brother Granite Company. 

FrencMown. 

At the eastern end of the high suspension bridge of the Baltimore 
and Ohio Railroad over the Susquehanna river there is a small quarry 
opened in a schistose granite, which is very similar to that worked 
at Port Deposit. This quarry was probably first opened during the 
construction of the railroad bridge,' but nothing of economic import- 
ance was done here until the firm of Wm. Gray and Sons of Phila- 
delphia became interested in 1894. At this time the capital invested 
was about $8,000, a sum which represents but part of the present 
investments. No work of any particular moment was done by the 
present owners until the autumn of 1896, when the receipt of some 
moderate sized contracts encouraged the further opening of the 
quarry, which now bids fair to establish a well organized industry at 
Prenchtown. The only buildings of importance which have been 
built from the Frenchtown rock are the Cold Storage Warehouse and 
and an extension of the Baldwin Locomotive Works in Philadelphia. 

The location of the quarry topographically and geologically is simi- 
lar to that of the quarries at Port Deposit. The ground is stripped 
upon the side of a hill and the quarry has worked down to the level 
of the low bench, along which runs the Port Deposit and Columbia 
Eailroad. The jointing of the rock is similar to that at Port Deposit, 
and there are here three prominent sets of joints intersecting approxi- 
mately at right angles. Members of the same series are so placed 
as to facilitate working of the quarries and blocks containing 3,000 
to 4,000 cubic feet might easily be obtained. 

The texture of the rock like that at Port Deposit is coarsely gran- 
ular, with a secondary lamination, and is adapted to all ordinary uses 
in general building, exterior ornamentation, curbing, paving, etc. It 
is possible, however, that this rock may be a little more " plucky " 
in working than the larger deposit farther north. This difference in 
the ease with which the stone is worked seems to be a temporary 

' The main piers of the bridge are built of Port Deposit granite. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XI. 




GRANn E-PORI'llVRY. 

ELLir.OTT CITY. HOWAKD COtlNTV. 



MAEYLAND GEOLOGICAL SURVEY 147 

feature which may have disappeared before the publication of this 
report. Like the rock quarried at Port Deposit, that at Frenchtown 
frequently appears somewhat disfigured by small black patches or 
basic segregations of biotite, which often render the stone unavailable 
for the highest grades of ornamental work. The microscopical char- 
acteristics of this rock as well as the color and texture are the same 
as those of the Port Deposit rock already described. The quarries 
have not been worked long enough to indicate by the product the 
durability of the rock or to call for discussions of its specific gravity, 
crushing strength and other physical features. There is no doubt, 
however, that the rock \vill respond readily to all the demands made 
upon it for ordinary building purposes, and that it will resist any 
pressure or atmospheric influences which it would normally encounter.' 
It weighs about 170 pounds to the cubic foot. ' 

The quarry as yet is small. At the time it was visited in 1896 the 
total space excavated was scarcely more than 5,000 square yards. In' 
1S97 the opening was fully twice that size. The transportation facili- 
ties are very good, the same as those at Port Deposit. The stone may 
be loaded directly on the cars for Philadelphia and Baltimore or ou 
barges for these and other coastwise points. 

Ellicott City. 

The Ellicott City granite area consists of an irregular L-shaped 
mass, which has an extreme length of about five miles in an east and 
west direction and a breadth varying from one-half to two miles. On 
the north, west, and south it is bordered by a large gabbro area; on 
the east by gneiss. A considerable portion of the granitic area of 
this district is overlain by Neocene gravels (Lafayette Formation) and 
Cretaceous clays (Potomac Formation), thus concealing from direct 
observation much of the rock in question. The elastics, however, are 
quite thin, and consequently all the rivers and even the minor water- 
courses have cut their channels down to the more resistant crystalline 
rocks. The boundaries of the granites, gabbros, and other massive 
rocks are thus capable of being determined with nearly as much accu- 
racy as if the sedimentary deposits were not present. 

The quarries of Ellicott City are situated nine miles by road from 



148 A HISTOEY OF THE QUARRYING INDUSTRY 

Baltimore and fifteen miles by railroad. They are located on either 
side of the Patapsco river in Baltimore and Howard counties, and 
tlie rock in which they occur extends on the eastern side of the Patap- 
sco as far east as Ilchester, but on the western side only as far as 
Grays. The material on the Baltimore county or eastern side is a 
fine grained mass, with a decided foliation or gneissic structure. On 
the opposite side of the river in Ellicott City itself it is more uniform 
and granitic. Here it also has a porphyritic structure iu consequence 
of the development of large flesh-colored crystals of feldspar which 
are disseminated somewhat irregularly through the rock, as shown in 
Plate XL 

The time of opening these quarries dates back probably into the 
last of the 18th century, but the details are entirely wanting. The 
beautiful appearance of some of the more uniformly porphyritic speci- 
mens early attracted attention, and in the earliest works which we 
have on this area, that by Dr. Hayden,' published in ISll, mention 
is made of these quarries. It is not certain whether the quarry on 
the Baltimore county side or the quarries of the Howard county side 
furnished the first material for Baltimore, but it is clearly evident 
from the character of the rock furnished for the Catholic Cathedral, 
that the gneiss was the more important rock at that time. Local 
tradition assigns the source of the stone sometimes to the Baltimore 
county side and sometimes to the Howard county side and tlie pub- 
lished infoi-mation is equally conflicting and indefinite. "When the 
Cathedral was constructed during the years 1806 to 1812 and subse- 
quently from 1815 to 1821, the material was hauled from Ellicott 
City to Baltimore along the old Frederick road in huge wagons drawn 
by nine yoke of oxen. After furnishing the rock for this building, 
which must have been one of the most important stone structures in 
the United States at the time of its construction, the quarries evidently 
were worked only to meet local demands. In fact they have never 
since been of such relatively great importance. Dr. David Dale 
Owen, indeed, while studying the various building stones of Mary- 
land at Cockeysville, Woodstock and Port Deposit, with the view of 

' Geological Sketch of Baltimore, see Bruce's Amer. Min. Jour., vol. I. 
New York, 1814, pp. 243-248. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XII. 








_ - -* ■. 



..w*. 



-tt'^X 




'*^.y'"^^y^m^^ 




yic. I.-GAITIIKR-.S (jr.\i:iiY, KI.I.ICdTT CITY. 




Fig. •->.-WEHKR'S UUAHltY, KI.I.II :i lir CllY. 



MARYLAND GEOLOGICAL SURVm' 14!) 

training all the information for the Smithsonian Imilding, twice passed 
by these quarries and yet makes no mention of them. At the time 
of the Tenth Census the agent remarks that lie '' knows of no other 
place in the coimtry where there are so many stone hnildings in an 
area of the same size." 

Of the quarries in operation at the present day those of AVerner 
Bros, were opened as early as the beginning of the century. In IS72 
Charles J. Werner reopened a quarry, which since his death in 1888 
has been operated by his sons, who purchased in 1890 a second quarry, 
which liad previously been opened by Kobcrt Wilson. These (luarrios 
became of some importance in 1893, when one of them is spoken of 
as the principal Ellicott City quarry, although it is now producing 
little or no building stone except during the fall of the year when 
random rubble is quarried for local use. The output for the year 
1896 did not aggregate over 200 perches. The most active quarry 
at the present is that operated by A. Weber (see Plate XII, Fig. 2). 
This quarry is situated on the Howard county side some distance below 
the station. The material has been furnished in recent years for 
some important buildings, as those of the Woman's College of Balti- 
more, but most of the material seems to be used for Belgian blocks, 
curbing and macadam. 

'I'hc system of joints in the region under discussion are not regular, 
but intersect at varying angles and at different distances. In the 
Weber quarry there is one prominent series of bedding joints, which 
strikes in a southeasterly direction and dif)s at a low angle into tluV 
hill. Besides this principal series there are four or five others with 
more vertical dips and varying strikes, which free the rock in huge 
irregular blocks. The jointing is so prominent and so irregular that 
it modifies the manner of quarrying quite perceptibly, as the stone 
is first obtained in irregidar masses and then worked into desired 
form by hand. Such a process increases the cost of operation, but at 
the same time furnishes considerable random rubble of a size suitable 
for ballast ami rough road material. Across the river from the Weber 
(piarry, in the opening worked by Gaither, the jointing is more regular 
and the face of the quarry is seamed into innumerable rhomboids 
several feet in diameter (Plate XII, Fig. 1). 



150 A HISTORY OF THE QUAEEYING INDUSTRY 

The opportunities for shipment and drainage are good. Those of 
the Weber quarry are seldom excelled, as the opening is in the side 
of a hill so close to the tracks of the Baltimore and Ohio Railroad 
(main stem) that cars may be loaded simply by turning the derrick 
boom. 

Probably no area of granite within the state shows as great varia- 
tion in the texture and the character of the rock as that about Ellicott 
City. In the quarries on the eastern side of the river the rock ap- 
pears quite schistose and homogeneous, and practically lacking in 
porphyritic crystals. Through it are scattered large patches or se- 
gregations of the darker minerals, which give to the rock the some- 
what sombre effect displayed by the Baltimore Cathedral. These 
patches do not weaken the rock, thovigh they render the stone less 
attractive. On the other side of the river, as has been mentioned 
already, the stone has a distinctly porphyritic character, which gives 
to it a mottled effect, well shown in Plate XL The increased amount 
of feldspar brightens the rock and the distribution of the crystals adds 
detailed variety to the structures in which it is used. 

The microscopic texture of the porphyritic type is shown in the re- 
produced photomicrograph (Plate IX, Fig. 2) where the grains are 
represented ten times their natural size. There is nothing particularly 
noticeable in the arrangement of the constituent since they unite with 
interlocking sutures, as already described in the discussion of the Port 
Deposit granites. 

Woodstoch. 

Perhaps the best granite in Maryland for general building purposes 
is that which is found in the small area in the southwestern corner of 
Baltimore county near the railroad station of Woodstock, Howard 
county. Woodstock is situated on the main branch of the Baltimore 
and Ohio Railroad in the valley of the Patapsco twenty-five miles 
from Baltimore. It is a small coimtry hamlet, but serves as the ship- 
ping point for the granites, which are quarried about one and one-half 
miles to the northeast. Within the area of the quarries is the small 
town of Granite, which was formerly known as Waltersville. Ac- 
cording to the account of Mr. Arnold Blunt,' " boulders first attracted 

• Maryland, its Resources, Industries and Institutions, Balto., 1893, p. 120. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XIII. 




GRA.NITK 

\V.M,1 ERSVII.LK. IIAI.'I IMORli tOl'NTV. 



MARYLAND GEOLOGICAL SURVEY 151 

attention and were worked by several enterprising men from New 
Hampshire, who commenced their operations here about the years 
1832-33. Among them were the names Sweatt, Riddle, Putney, 
Holbrook, followed by many others, among whom were the Emorys, 
Gaults and Eatons. The principal demand was at first by the Balti- 
more and Ohio Railroad for stone stringers, dressed to correspond to 
the flange and tread of the car wheels, and also ashlar, &c., for their 
bridge and culvert work." 

Although prospecting has been carried on ever since, only two 
ledge quarries have been discovered, viz. : the " Waltersville " and 
" Fox Rock." The former is the principal one, and was at first 
called the " Branch." This rock developed into a fine ledge, sur- 
passing all the granite around in quantity, quality and easy access, 
so that all the boulders in which Sweatt, Putney and Riddle were 
interested were at once abandoned. After working it for a year or 
two Putney and Riddle obtained a lease of this quarry for twenty years 
in August, 1835, from the owner, Captain Alexander Walters, to 
whose family this quarry has belonged for more than a century. It 
is called in the lease and is still known as the Waltersville quarry, 
although the name of the village of Waltersville was changed to Gran- 
ite about 1873-74, when the first post-office at the place was estab- 
lished. The lessees went to work vigorously, and besides many other 
improvements, built a railroad two miles long to connect with the 
Baltimore and Ohio at Putney and Riddle's bridge, about one mile 
east of Woodstock. Their first contract of importance was furnishing 
stone for the Baltimore Custom House. They, however, continued 
the business only a few years. Extravagance and mismanagement 
caused the failure, and they were succeeded by Edward Green and 
Joshua B. Sumwalt, under the firm-name of Green & Sumwalt. The 
senior partner dying about 1849, he was succeeded by his son Fred- 
erick, and the firm became Sumwalt & Green, who conducted the 
business until 1865, when Attwood Blunt, whose wife owned the 
property, took charge and continued the business until 1871, when the 
quarry was leased to Ansley Gill and James McMahon. After a lapse 
of about sixteen years, the firm was dissolved by the death of 



152 A HISTOEY OF THE QUAEKYING INDUSTEY 

McMahon. Mr. Gill continued the business alone for a short while, 
when he associated with him Wm. H. Johnson, of Baltimore, and 
they soon after formed with George Mann, Hugh Hanna, Messrs. Grey 
& Sons, of Philadelphia, and Mr. Hamilton of Baltimore, a joint 
stock company, calling it the Guilford and Waltersville Granite Co. 
This company is now conducting the business. 

The rock from the Woodstock area was early used, as indicated in 
the preceding sketch, but the first published account of it which 
attracted attention was that by Dr. David Dale Owen.' In his report 
to the Building Committee of the Smithsonian Institution he says: 
" During the examination of structures and monuments of Baltimore 
marble, both in Greenmount cemetery and in the city of Baltimore, 
with a view to ascertain the durability and facility of working this 
material, I was so miich stnick with the beaiity of some of the granite 
vaults and fronts of buildings that I determined to visit the quarries 
from whence this material was prociired. . . . Accordingly I stopped 
at Woodstock, 16 miles beyond the Kelay House, and inspected care- 
fully the Waltersville branch and the Fox Eock quarries in this vicin- 
ity; both of which are well opened, and afford a good opportunity of 
judging the quality and extent of this formation. 

" For about a mile square at this locality is an outburst of quartzose 
granite of magnificent quality, both as regards beauty of appearance, 
compactness of structtire, and uniformity of color, texture, and com- 
position. I have never seen anything superior in this country; in- 
deed, I doubt whether it can be excelled in any country 

" Fidly to appreciate the quality of this granite, the quarries them- 
selves must be visited, and the huge blocks in mass inspected as they 
are removed from their original bed. There, one may see a perpen- 
dicular face of nineteen feet presented to view, extending twenty, 
thirty, and even forty or fifty feet, without a seam or fiaw, or the 
slightest variation in hue. A mass of forty or fifty tons weight may 
often be seen severed from the parent rock, by the simple but effective 
means of small iron wedges. . . . The Fox Eock quarry is thirty-six 
feet from top to bottom, where now excavated. It might be worked 

' Report of the Board of Regents of the Smithsonian Institution, Jan. 6, 
1848. Senate Doc. 30th Congress, 1st Session. Miscl. No. 23, pp. 31-32. 



MARYLAND GEOLOGICAL SURVEY 



VOLUME II, PLATE XIV. 








KS74 







Fic:. 1.— WELIiER'S OUAHHY. CI! A.\'frK. HA l/l'l MnllE C.orNTY. 




Kic. 2— C.UJI.FOUD A\U WAl.Tlll'.SVII.I.K urAllliV. ( ; I! AXril'). IIAI.II M()I!K niirNTV. 



MARYLAND GKOLOGICAL SUKVEY 153 

some fifteen or twenty feet lower before being incommoded by water. 
Jfortar adheres with such force to this granite, that, when fairly set, 
it requires as much force to separate the substance of the granite as 
to detach tlu^ mortar from the face. 

■' On the whole, the inspection of these granite quarries has im- 
pressed me with the belief that no locality can furnish a superior qual- 
ity of granite, and that it cannot be surpassed for strength and dura- 
bility by any building-material in the world." 

'J"he letters which accompany this report show that in 1847 the 
firm of Sum wait. Green & Co., evidently composed of Edward Green 
and Joshua B. Sumwalt and his son Frederick, earned on the business, 
and the size of the quarries, as indicated in the remarks of Dr. Owen, 
shows that the business had already reached a considerable import- 
ance. Perhaps as the result of this report by Dr. Owen, the contract 
was granted for furnishing the foundation stone, which was used in 
an extension of the Patent Office Building constmcted in 18-19, ami 
the Postoffice Building, in 18.55, although some of the Woodstock 
granite had lunni used in the general Postoffice before 1847.' 

The gi'anite mass as indicated by the map forms a more or less oval, 
isolated area of granite extending scarcely two miles northeast and 
.tonthwc-t and a mile imrthwcst and soutliea:it. .\lthough so small, 
it is one of the most important economic areas within the state. This 
ma.ss of granite, which is evidently intruded into the gneisses, is en- 
tirely enveloped by them and sends no dikes or apophyses into the 
surrounding rock. That the gneiss is really older than the granite is 
shown by the great number of inclusions found within the latter. 
These are chiefly of gneiss, and th'ey occur often in huge irregvilar 
blocks six to eight or even ten feet in size, showing narrow rims due 
to contact metamorphism. They are beautifully puckered and 
wrinkled and being much richer in ferro-mag-nesian silicates than the 
granite itself, their irregular outlines contrast sharply with the lighter 
background. (The darker portion of the large block in the center of 
Plate XIV, Fig. 2, is included gneiss.) 

The most marked feature of these quarries, especially in the Wal- 
tersville quarry (Plate XIV, Fig. 2), is the sharp definition of the 

' Loe cit. p. 41. 



3 54 A HISTORY OF THE QUAKRYIKG INDUSTRY 

systems of vertical and horizontal joints which are so prominent and so 
persistent in their horizontal extent, that they at first glance give the 
impression of stratification. They strike approximately north 60° east 
and dip at an angle of 10°-15° to the northwest. The joint faces are 
not planes, but ai'e curved more or less irregularly. The figures given 
represent the general strike and dip as seen in the Waltersville quarry, 
hut even these somewhat generalized values are not persistent over the 
entire area, for in the center of the Weller quarry, which abuts upon 
the Waltersville quarry on the west, the strike and dip changes com- 
pletely within the distance of a few feet. This irregularity in the 
joints has caused considerable trouble in the quarrying, although 
when visited the ledge worked was well exposed, and the blocks were 
large and easily obtained. The accompanying figure (Plate XIV) 
shows how large slabs and blocks may be freed at little expense. The 
piece in the center of the picture has been separated from the ledge at 
the back by a series of wedges, while it was only necessary to use a bar 
to pry the mass from the ledge beneath. There are fully five or six 
series of joints which are distributed without any marked uniformity 
through the mass. Besides the main horizontal joints there are others 
at a slight inclination, which continue for a short distance and then 
die out. The vertical joints show several planes oriented in different 
positions and showing variable dips and uneven surfaces. 

This jointing is sharply brought out by the weathering of the rock. 

" The quarry ledge has the appearance of a great wall of cyclopean 
masonry, layer upon layer of huge blocks rising one upon another 
with the regiilarity and precision of human workmanship. The sepa- 
rate blocks are more or less oblong in shape, and often measure 15 to 
20 feet in length and from 2 to 8 feet in height. They are all more 
or less rounded, the spaces between the different boulders being filled 
with incoherent granitic sand, derived from the decomposed edges 
and the sides of the blocks. It is quite evident that the granitic mass 
was originally everywhere jointed, and that atmospheric decay took 
place much faster on the edges and corners than on the flat sides of the 
great fragments, thus quickly rounding and forming them into boul- 
ders like those found throughout drift areas. The sandy matrix is 



MARYLAND GEOLOGICAL SURVEY 



VOLUME II. PLATE XV. 




ni:rAii.i:u \ ii:w. WKi.i.Kirs urAiniY. c.ii.wni:. 



iMARVI.AXD nKOLOGICAI. SDEVEY 155 

usually from 5 to 10 inches in tliickness. The interior of the boulders 
is perfectly fresh, and affords the best of rock for building purposes. 
As decomposition progresses the amount of interstratified sand greatly 
increases, and the blocks become proportionately smaller." 

This method of weathering facilitates the early workings in a quarry 
and so brings the rock into notice, but there is necessarily a great 
deal of waste and considerable expense in bringing these boulders 
into rectangular form unless there are well defined seams or a " grain " 
running through the rock, as is the case at these quarries. The grain 
(jf the rock is so marked that it cannot fail to impress any thoughtful 
observer who %asits the quarries.' 

The jointings in the Fox quarries are not as strongly brought out 
by weathering as they are in the Weller and Guilford and Walters- 
ville quarries although the different sei'ies are distributed in about 
the same manner. At the time of inspection, these quarries, which 
are operated by the Gaidts, were not in active operation, although 
considerable material suitable for furnishing Belgian lilocka and ran- 
dom rubble was scattered about the pits. 

The appearance of the Woodstock granite is well represented in 
Plate XI IT which reproduces tlie polished surface in natural size. The 
color of the rock is bright gray, with something of a luster imparted 
by the quartz and the unaltered feldspars, the latter often giving an 
additional faint pink tone. The mica occurs in evenly disseminated 
fine black flakes which emphasize the grain of the rock and only 
slightly subdue the bright fresh aspect of the stone. The size of the 
constituent grains which varies from 0.05-0.2 inches in length, and 
from 0.01-0.10 inches in breadth, for quartz and feldspar, is little 
marred by the less resistent mica wearing away and leaving small 
depressions, that arc scarcely discernible to the naked eye. The pol- 
ished surfaces, such as are represented in the plate, are darker than 
the rough or ashlar finished stone. 

The chemical composition of the I'ock, as indicated in the following 
analysis by Mr. Hillebrand,' shows the rock to be somewhat siliceous 

■ See ante p. 152 and Plate XIV. Fig. 1. 

' Report of Work done in the Div. of Chemistrj' and Physics. Bull. No. 
no, IT. S. Geol. Survey. (1890-91) Washington, 1892. p. 67. E. 



156 A HISTORY OF THE QUAERYIXW INDUSTRY 

and yet particularly rich in lime. This marked increase iu the per- 
centage of CaO is explained by the presence of considerable allanite 
and epidote in the rock. It is therefore not a source of contamination, 
for the epidote is particularly stable under atmospheric conditions. 
The percentage of the alkalies is moderately high, while the iron and 
magnesium content is very low. The rock, accordingly, possesses 
great durability and power of resistance toward atmospheric decompo- 
sition. 

SiOj 71.79 

AIjO., 1.5.00 

Fe.Oj 0.77 

FeO 1.13 

CaO 2. 50 

MgO 0..51 

K,0 4.75 

Na.,0 3.09 

H.p 0.64 

100.17 

The tests to which sjiecimens from the Walters\'ille quarries have 
been subjected show the rock to be all tliat could l>e desired for 
strength and durability. The strength of the stone is several times 
that of brick, and the percentage of absorption is very low, showing 
that the stone can withstand both pressure and the deteriorating action 
of frost. The figures obtained are as follows: 

Simple crushinix. Absorption. Freezing. Crushing after freezing. 

Cracli. Break. Percentage of gain. Percentage of loss. Crack. Break. 

79,700 85,700 O.S.'iS 0.011 79,400 103,200 

79,200 83,430 0.333 0.039 86,800 90,300 

Guilford. 

Perhaps the most attractive stone found within the state is that 
which is quarried at (hiilford in Howard county, about five miles 
northwest of Annapolis Junction, on the Little Patuxent river. This 
granite early attracted attention because of the uniformity and fineness 
of its grain, its light color and pleasing effect. Although the area 
furnishes excellent monumental and building material it is unfortu- 
nately situated some miles north of the Baltimore and Ohio Kailroad, 
a circumstance which has delayed such a development and recognition 



f^ 



ilAKVLAKD GEOLOGICAL .SIKVEV 157 

of tlie rock as the material deserves. At present tli(;re is a sidetrack 
whicli runs from the Baltimore and Ohio Railroad to Savage Factory 
only two miles distant. This distance, however, with the necessary 
haiilinji', is sufficient to render successful competition with more favor- 
ably deposits soiuewhat doubtful. 

The quarries at Guilford were originally opened about 183-4, and 
were worked almost continuously from that date until the outbreak 
of the ci\al war in 1800. Diiring the suc(^eeding twenty-five years 
the operations were of little account, and little work was done until 
the Guilford and "Waltersville Granite Company attempted to develop 
the industry in 1SS7. This elfort lasted but a short time as all of the 
machinery was removed from the quarries in 1889. The industrial 
life of the district has been revived somewhat in recent years by the 
operations of Messrs. ^Matthew Gault and Sons, who conuuenced work 
in ^S[}^d, and by Messrs. Brunner and White, wIkj opeued a quan-y of 
superior quality in March, 1895. 

The Guilford granite is bordered on the north and west by the 
Piedmont gneiss and on the east by the gabbro. It is also in part 
covered by the gravels and clays of the Potomac. The jointing of the 
rock is sharp and usually regular, the individual planes being suffi- 
ciently far apart to allow the quarrying of blocks of any reasonable 
size; at the same time they aid materially in the freeing of the stone. 

The rock of this area differs from all of the other granites of the 
state in the persistent presence of both light and dark colored micas. 
Thus, according to the German classification, it is the only '" true 
granite " ' in the state. Other granites may have muscovite as a con- 
stituent, but it is not so alnmdant or typical as in the present instance. 
Both of the micas arc products of the original crystallization of the 
molten rock magma, and they are frequently in parallel growths. 
The biotite, which is especially rich in iron, possesses a very dark color, 
but shows no evident disintegration or decomposition. The feldspat 

' The use of this term in i^revious papers on the granites of Maryland 
has led to some misunderstanding- on the part of quarrynien. In this 
petrosraphical sense as applied to granites " true " has not meant that all 
of the granites of .Maryland with this exception are " bastard " granites, 
but it has only meant that this gi-anite corresponds to the " zwei-glimmer " 
or " echte granit " of the (ierman classiflcation. 



158 A HISTORY OF THE QUARRYING INDUSTRY 

is almost entirely microcline, which shows the cross-twanning veiy 
clearly, and appears clear and fresh with very few included flakes or 
small cystals. These microclines form the largest individual areas in 
the rock mass, sometimes reaching 0.15-0.2 of an inch (4-5 mm.) in 
diameter, while the clear transparent grains of quartz average less 
than 0.01 of an inch (.03 mm.). The individuals are interlocked in 
a mosaic, which indicates that the rock can well withstand any pressure 
to which it may normally be subjected. The mica flakes are small 
and evenly disseminated, so that they do not injure the polish which 
may be given to the rock in preparing it for monumental purposes. 

Mino7- Areas. 

Besides the five areas already described there are several other gran- 
ite masses within the state, as indicated by the map, which have been 
worked from time to time to supply the local demands, and occasion- 
ally with the hope of bringing the stone into commercial importance. 
Of these smaller masses which have been quarried spasmodically the 
most important is that of Dorsey's Run on the Baltimore and Ohio 
Railroad between Ellicott City and Woodstock. The stone of this 
area was first quarried for use on the Baltimore and Ohio Railroad 
to protect the roadway from the encroachments of the Patapsco. These 
and subsequent operations have developed two or three quarries which 
have furnished about 10,000 cubic feet each, since they were first 
opened. The proximity to the railroad has been of advantage and 
efforts were made in 1893 by Mr. W. B. Gray of Baltimore and 
Messrs. Peach and Feenay of Woodstock to develop a trade in curbing 
and paving blocks. The quarries at the time of writing, however, 
have suspended operations. The ledges furnish blocks of 40 or 50 
cubic feet, but the product seems to be overshadowed by that of the 
neighboring quarries in Ellicott City and Woodstock. 

In 1888 Mr. W. F. Weller of Granite leased a quarry near Sykes- 
ville, and began somewhat later the quarrying of Belgian paving 
blocks, which was continued for some year and a half. At the present 
time this quarry is not in operation, and no others are at present 
worked in the vicinity. 

On the southern prolongation of the Sykesville mass near Garrett 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XVI. 




FINE-GRAINEP (.RA.MTE. 

'■' i< i-ORI>, HOWARD COUNTY. 



A 



MAEYLAND GEOLOGICAL SURVEY 159 

Park and Brookville is a quarry operated by John A. Riggs, which 
was probably first opened about the beginning of the century, from 
which time it was occasionally operated in a small way up to 1881. 
The total amount of stone extracted, however, does not exceed 1000 
perches. INTo large stone can be obtained from the present opening, 
as the rock is much broken into blocks, which contain scarcely 20 
cubic feet. This opening, however, is in a poor place and the best 
stone has apparently not yet been reached. Since the distance from 
the railroad renders this rock unavailable for city demands it will 
probably never be of more than local importance. Some twenty-five 
years ago a second quarry was worked at Brookville in rock which 
was good for local requirements. This was opened in 1850 and some 
1000 perches of rock were obtained between 1850 and 1870. The 
granite exposures at Garrett Park embrace several small outcrops 
of which the best are those along Hock Creek. At several of these 
small exposures, quarries have been opened and worked from time to 
time to supply the local demand. 

Probably the most extensive operations carried on in Montgomery 
county are those near Cabin John, in a quarry operated by Mr. Gil- 
bert. This quarry was opened aboiit 1850 and there have been exca- 
vated probably 1,500,000 cubic feet. The rock is a schistose granite 
rather dark gray in color, and suitable for general building and road 
metal. In the quarry there are three prominent sets of joints, which, 
however, are so placed as to permit the quarrying of large blocks. 
Already pieces containing 1000 square feet have been obtained. The 
mode of transportation from the quarry to "Washington, a distance of 
six and one-half miles, is the Chesapeake and Ohio Canal, which has 
rendered the location so available that the rock has supplied some of 
the demand for foundation stone. At the time when the quarry was 
visited operations had been suspended and the machinery on the 
ground was unused and going to ruin. 

At l""ranklinville on the Little Gunpowder, three miles north of 
Bradshaw's Station, are exposures of a schistose granite resembling 
that quarried at Port Deposit although somewhat darker and even 
more schistose. This rock has not been quarried as much as its posi- 
tion and character mie,'ht warrant. It is owned and worked by the 



160 A HISTORY OF THE QUAEEYING INDUSTRY 

Cotton Duck Factory Co. It has supplied the local demands and 
there have been quarried about 1000 perches a year for the last seven 
or eight years. Large curbing blocks might be obtained easily, as 
blocks 11' X 2' X 1' have been quarried. The opportunities for oper- 
ating are good, as freedom from water and large dumping grounds 
are features of the location. The distance, however, from the rail- 
road might be a serious drawback. 

In the town of Benson, Harford county, there is a small opening 
for granite, where quarrying was first carried on in 18S5. The out- 
put is small, not reaching 1000 perches a year, and yet from this lo- 
cality was furnished the material for one of the churches in Bel Air. 
The quarry, which is owned by Mr. L. Amoss, is situated near Win- 
ter's Kun on the Harford pike and was never opened %vith the inten- 
tion of operating it extensively. The stone is in boulders and is easily 
worked by hand. On exposure it becomes lighter and more pleasing 
in color. 

Near Baldwin's Station, Cecil county, is a small quarry of schist- 
ose granite, which supplies some of the local demands of Elkton, 
Maryland, and IS^'cwark, Delaware. This quarry is on the farm of 
Levi L. Hammond and was opened in the year 1842. The opera- 
tions are small, the' average yearly output reaching perhaps 2000 
cubic feet. Blocks containing 1200 feet have been obtained, and 
even larger might be quarried, if the facilities for handling were at 
hand. The quarry is only worked occasionally for building stone, 
which is sold by the perch. 

GNEISSES. 

Certain of the more uniform and compact gneisses furnish first- 
class building material and many quarries have been opened in the 
areas where the demand is great and the expense of handling and 
transportation is fairly low. These quarries are especially noticeable 
in the vicinity of Baltimore where all of the conditions are fulfilled. 
The gneisses of the area, represented on the map, show great constancy 
in their mineralogical and textural composition. They are composed 
of alternating bands of fibrous to micaceous hornblende, biotite and 
chlorite schist between lighter colored more or less feldspathic quartz- 



MARYLAND GEOLOGICAL SURVEY 161 

schist. Tlie dark ferruginous bands break down readily and are not 
used at all as structural material, but are discarded as waste. The 
best material comes from those portions of the lighter bands which 
are composed almost wholly of quartz, the prepared blocks differing 
but little from those made of a well characterized quartzite. The 
rocks are rather strongly bedded in slabs from one quarter to three 
feet in thickness, and are thus more easily worked than the hardness 
of the rock might at first suggest. The areal distribution of the 
gneisses, as represented by the accompanying map, clearly shows that 
the structure of the area is intricate and complex. The general trend 
of the formation is north-northeast and south-southwest, with a similar 
strike for the foliation, which usually dips to the northwest at a high 
angle. In the region adjoining Baltimore the structure, as indicated 
by the contacts and the position of the foliation, is still more compli- 
cated by sharp folds, faxilts and intrusive masses. Beginning east of 
Catonsville the strike of the foliation (probably nearly the same as 
the original bedding) becomes more and more northerly, until at 
"Woodberry it turns quite rapidly to the east and southeast crossing 
Jones' Falls south of Hampden with a trend somewhat north of east. 
The strike about Lake Montebello (Baltimore city) seems to radiate 
in a fanlike manner to the northwest, north and northeast. About 
Lake Roland and the Bare Hills this structure becomes even more 
confused, and yet preseiwes a general parallelism with the gabbro- 
gneiss boundary. 

The quai'ries about Baltimore are grouped around two centers, 
Jones' Falls and Gwynn's Falls, on the northern and western sides of 
the city, the location being determined by the facilities afforded by the 
shape of the country for opening and working the quarries on a hori- 
zontal plane. This method of working decreases the cost of handling 
the stone, avoids any expense or difficulties because of water and often 
furnishes a convenient and cheap dumping ground away from the 
rock bed which may be worked in the future. 

Jones' Falls. 

The quarries on Jones' Falls were originally opened at some distance 

from the city, as they were in operation probably before the beginning 
11 



Ifi2 A HISTORY OF THE QUAREYING INDUSTRY' 

of the i^rescnt centnrv. The first mention of them is found in a 
rare jonmal' published in Baltimore in 1811, where the following 
words occur in a description of the geology of Jones' Falls: " Imme- 
diately above this [a pegmatite dike] it [the gneiss] assumes nearly 
the texture of the first mentioned, being fine, hard and compact, and 
gradually passing through the above transitions, until, at one mile 
and a half from Baltimore, it acquires a texture, siich as to render it 
highly valuable and useful in various branches of masonry, and as 
such, is here quarried on both sides of .Tones' Falls, to considerable 
advantage to the proprietors." 

The first quarries opened were probably situated on the right bank 
of the Falls about where the Mount Vernon shops now stand, and 
wei-e operated more or less continuously until the building of the 
Northern Central Railroad, about 1830. The (piarries on the left 
bank of the stream have been in almost continuous operation from the 
time of their opening until now. It has been difiicult, however, to 
gather any information regarding the various oi^erators who have 
been interested here. 

The occurrence of the quarries is all that could be desired. The 
rock is clearly bedded in sheets, ranging in thickness from four or 
five inches to five or six feet. These sheets extend with almost no 
break for considerable distances, as is shown in the accompanying view 
of the quarries leased by Messrs. John F. Curley and John G. 
Sehwind. The sharp light lines extending diagonally across the main 
sheet from left to right are small faults with a throw of a few inches. 
These sheets are rendered workable by two series of joints at right 
angles to each other, situated at favorable intervals. These are also 
supplemented by a '" grain " in the rock, which is at right angles to 
the bedding and nearly parallel to one of the planes of jointing. 
From this distribution of the lines of weakness, it is possible to free 
large blocks from the bed and then, if desired, the slabs may lie sepa- 
rated readily into smaller blocks. The angles of inclination between 
the planes of jointing, bedding and grain do not vary widely (usually 
10°-15°) from 90°, so that the stone may be squared without great 
cost. No dynamite is used in the qimrrving, but oeeasionally charges 

' Loc. cit. pp. 255-271. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XVII. 




Ki.;. l.-lMIOTOMlCliOcniAIMI OF CKAXn'K, (iK.WI riO. (MACNrFiKi) Ti-:x DrAMirriais.) 




Fig. S.-l'HOTOMliJHOGHAlMI OF GXKISS. ISAl.Tl.MORK. ( M.VG.MKiEn Tkx 111 ametehs.) 



MARYLAND GEOLOGICAL SURVEY 163 

of powder are employed to loosen the rock and thus render it easily 
separable along its joints and grain with the " ping and feather " 
wedges. 

The inclination or dip of the beds also facilitates the quarrying. 
It is usually about 45° to the northwest, so that the freed blocks may 
be easily handled. There are two methods of utilizing this dip. In 
the Pcddicord quarry on the Falls road the operations are carried in 
horizontally aJoiig the strike, and then the vai-ious beds are worked 
from the top and side. In the Curley-Schwind quarry, where the 
same beds are exposed, the " head " is first driven in across the strike, 
and then the beds are worked along the strike. 

The texture of the different sheets varies considerably, Imt tli(> first 
quality rock runs quite uniformly. It always shows a huninatinn 
parallel to the original sheeting and should therefore be laid on its 
bed in structures. The quartz and feldspar grains are of approxi- 
mately the same size and unite with the small mica plates to form a 
uniformly textured rock of dark gray color. The different beds vary 
somewhat among themselves in the size of the grain, in the relative 
amount of quartz and feldspar and in the amount of lamination. As 
is true of many sedimentary gneisses, this difference in the dark and 
light bands is so well defined that the quarrymen by a little sorting 
may furnish niaterial wliieli will run uniforuUy for individual ship- 
ments. There will, however, be some difference between different 
shipments, unless considerable care is exercised by the quarry master. 

The color of the roek has been given already as dark gray, but from 
this there are uuuiy \ariations, with a range from very light gray to 
a dark sombre, vitreous blue-black. The variation depends upon the 
amount of feldspar and mica present. If the rock is composed almost 
entirely of clear, vitreous and pellucid quartz grains the rock is usually 
dark and cold whether there is much mica present or not. AVhen 
felds])ai' is ]iresent or tlie gi'ain of the rock lieeouies fin(^ or saccha- 
roidal the color of the rock is brighter and more pleasing. The 
amount of mica present in the feldspathic fine grained rock seems to 
have a greater eft'ect on the color than is the case in the more quartz- 
ose varieties. This constant blue-iirav tone in tlie color of the rock 



164 A IIISTOEV OF THE QUARRYING INDUSTRY 

has led to the application of the local term " blue stone," which is 
current among the qiiarrymen and is often introduced into contracts." 

The chemical composition of the gneiss is so variable that single 
analyses cannot represent the character of the whole mass. A fair 
representation of the composition of the lighter colored gneiss would 
show the silica rather higher than the average. A microscopical study 
of these same lighter bands, which are used the more extensively, 
show that the constituents do not always interlock, although there 
has been considerable growth of the quartz grains since the rock was 
formed. These are indicated by the light veins about many of the 
grains in Plate XVII, Fig. 2. Most of the grains are somewhat 
rounded, suggesting that the gneiss is of sedimentary origin, and the 
interstitial spaces are filled with more finely comminuted fragments 
of quartz, feldspar and secondary minerals. Among the last are epi- 
dote, garnets and occasionally fibrolite, cyanite and staurolite.' 

The chemical and mineralogical composition of the Jones' Falls 
rock show that the individual constituents are not liable to decom- 
pose readily and that there are few minerals occurring as accessory 
constituents which really vitiate the rock. On the other hand, the 
crnshing tests show that there is a much more marked tendency to 
physical disintegration in certain directions. The rock to be service- 
able must, therefore, be placed in the wall in certain positions only. 
The results of the tests are as follows: 

Crushing. Absorption. Freezing. 

Percentage of Percentage of Crusiiintr 



CracU Break. gain. loss. after freezing, 

yuartzose layers ( 66,700 70,140 0.197 0.038 80,118 118,000 

("Blue Stone.") f 85,940 96,300 _ 

Feklspathic layer ) 94,300 ' l.lli; 0.0.53 (;3,060 84,830 

("B. granite.") j" 78,000 103,500 

' This term " blue stone " is a iJOiiular one which is applied to different 
rocks in different localities; e. g. in the District of Columbia it signifies a 
mica schist; in Pennsylvania and New York a blue-gray sandstone; in Ohio 
a gray sandstone. This last tisage has become so common in the trade that 
it is hardly proper to call the Baltimore gneiss a " blue stone." 

- On the faces of the joints where there has been a little space after the 
movement of the rock there are often found haydenite (chabazite), laumon- 
ito, harmotome (or phillipsite?), stilbite, beaumontite (heulandite), siderite, 
pyrite, barite, haloysite, epidote, garnet, and tourmaline. See Notes on the 
Minerals occurring in the neighborhood of Baltimore by George H. Wil- 
liams. 17 pp. Baltimore, 1887. 



.MAHVI.AXl) GEOLOGICAL SURVEY 165 

The quarries show that the rate of decomposition and disintegra- 
tion is really very slight for gneisses standing at so steep an angle 
that the surface waters may saturate the rock with great freedom. 
There is, of course, considerable stripping required in some places, 
but when it is remembei-ed that these rocks, unlike the rocks farther 
north, retain the evidences of exposure to the destructive agents of 
the soil and atmosphere since Cretaceous time, certainly several mil- 
lion years, the amount of weathering seems insignificant. 

The most serious drawl)ack is not in any possible line of weakness, 
l)ut in the color. AVheu pieces of gneiss from different layers are 
intcrniinglcd willuMit any t-aro or arrangement, the effect is not pleas- 
ing, but qiiite the reverse. There is ciirrent an impression that the 
material for the Cathedral in Baltimore came from the Jones' Falls 
quarries, a view which is scarcely in harmony with the statement of 
Mr. Robert (!ilmor, Jr.,' in which lie describes how the material was 
brought from the Falls of the Patapsco about ten miles out on the 
Frederick pike. Part of the material may have been furnished from 
the nearer source, but Tmder these circumstances it would probably 
have been from the quarry on the right bank and not from any of 
those on the left bank, since the former was then the more important 
source of material, ^loreover, certain buildings such as the old 
Court House, portions of the Jail and some of the buildings at the 
Woman's College show that the rock may give a pleasing effect in 
structures. The demands at the present time are satisfied by higher 
grade material, such as the Port Deposit or Woodstock granite, and a 
large part of the gneiss quarried is employed either for foundations 
and pa^dng or as a backing for the more pleasing stone. 

The quarries in operation at the time of inspection by the writer 
were the Peddicord, the Curley-Schwind, and the Atkinson.^ Of 
these the Peddicord is the largest, showing an excavation of over 
seventeen million cubic feet; the Curley-Schwind shows about three 
million, and tlic Atkinson something over a niillinii cubic feet. 

' Bruce"s Anier. Miii. .lour., vol. i, .New York, 1S14, p. 2.12. See p. 126. 

■The ".\tkiiisoii " of the topograpliiu map is now the Peddicord and At- 
kinson is working- a smaller quarry a little farther northeast beyond the 
Curley-Schwind quarry. 



166 A JIlSTOltY OF THE QUAKEYING INDUSTRT 

Gwyn7i's Falls. 

The woi-k in tlio area west of Baltimore along the Gwynn's Falls 
and Gwynn's Run did not begin for some fifty years after that along 
the Jones' Falls, since the product lay to the west of the growing 
town and was sejoa rated from it by a series of ridges which increased 
the ci:ist of transportation. As the city extended westward, the supply 
from Jones' Falls became more expensive, and that from the small 
openings along Gwynn's Falls cheaper. The real work of the area 
began about 1850 and has continued without any marked abatement 
to the present time. The largest quarries in this part of Baltimore 
are operated by John G. Schwind, lessee and part owner of the large 
quarries on Edmondson Avenue, which are perhaps the largest and 
best equipped of any of the openings about the city. 

As shown upon Plate XYIII, Fig. 2, the rock of this quan-y is a 
gneiss, inclined at an angle of 30° and dipping to the northwestward. 
The general strike of the beds conforms to that of the area, which is 
north 45° east. As is the ca.se of the Jones' Falls quarries, the rock 
exposed in the quarries varies considerably, and furnishes two marked 
grades of material, one which is almost pure quartz resembling a 
quartzite and the other a much more feldspathic and micaceous aggre- 
gate very similar to the granite, but showing a greater or less per- 
fection in its bedding. 

In the qiiarry face the individual l)eds range in thickness from two 
to four feet, each showing great uniformity. The workable ones are 
clearly separated from each other, either by well defined bedding 
joints or by beds of inferior quality. Across each sheet are at least 
three sets of joints nearly at right angles to each other, which greatly 
increase the ease with which the material is extracted. The joints 
are separated from each other by distances ranging from a few inches 
to several feet, so that while facilitating the work they do not render 
the rock inferior, because of too great frequency. It is possible to 
obtain blocks of any size within the range of economical handling. 
This limit seems to be reached in blocks of seven or eight tons. The 
hoist in use, however, is capable of handling ten ton blocks. The pro- 
duct of these quarries is scarcely distinguishable from that already des- 
scribcd as characteristic for those of Jones' Falls. I-ike the latter the 



MARYLAND GEOLOGICAL SURVEY 



VOLUME II, PLATE XVIII. 




Fk;. 1.-CUKI.KY-SCH\VIND (HJAUKY. HALTIMOHK 




Fiu. -'.-"EllMMMISiiX a\1:M K' HI AlUtV. HAI.l'I.Mi Hil':. 



MARYLAND GEOLOGICAL SURVEY 167 

range in material is very wirle. All of the product furnished is un- 
affected by any considerable amount of deleterious minerals. The 
worst blemish arises from an occasional concentration of the feldspar 
individuals and nocnsioiially disseminated Innght pyrite crystals. The 
minerals, such as laumontite, stilbite, etc., for which the quarry is 
well known, do not occur within the body of the rock, but are secon- 
dary products distributed along the jointing planes. They accord- 
ingly are not injui'ious to its strength or weathering properties. Ma- 
terial has been furnished from these quarries for a good many well 
known buildings, especially in the city of Haltimore. Some material 
has also been shipped to Virginia. Peidiaps the most prominent 
structures which liave used this stone are the Traction Power 
House, a portion of the new Penitentiary and the Bolton Synagogue. 
In these buildings the stone is used chieflj' as a foundation stone, the 
superstructure being constructed in part of Port Deposit granite and 
in part of other domestic stone. Besides furnishing first-class founda- 
tion material the quarries utilize their waste by means of crushers 
in the preparation of crushed stone suitable for the construction of 
roads and gravel walks. 

The openings somewhat farther west, owned and operated by David 
Leonard, produce some of the best stone from this region. They 
were opened sometime prior to 1850 and have been worked more or 
less continuously ever since. The stone is very similar to that of 
the Edmondson Avenue quarry possessing the same marked bedding 
and several sets of joints, which allow the extraction of the stones in 
rectangular blocks of convenient size. It is probable that in this 
quarry the jointing is a little more irregular and the material fur- 
nished a little less satisfactory for the production of large blocks of 
foundation stone. This slight difference in the character of the ma- 
terial extracted has led the present owner to work a considerable por- 
tion of his stock into paving blocks. The distance of the luud and 
the sharp hill, which limits somewhat the load, increases a little the 
expense of furnishing the stone in the center of the city. The quality 
of the stone, however, which when cut is fully equal to that of any 
of the quarries about Baltimore, together with the uniform faithful- 



108 A HISTOKY OF THE QUAREYIKG INDUSTRY 

ness in fulfilling contracts causes a steady demand for the product of 
the quarry. 

In addition to these two quarries, there are others in the imme- 
diate vicinity, which are worked in a small way, furnishing a little 
material now and then for various local demands. These, however, 
change hands so frequently and are worked so irregularly that they 
do not seriovisly affect the market for stone of this general character. 

Besides the larger quarries of the area just considered there are 
scattered in various directions about Baltimore, especially to the east 
and north of the city, several others which have been worked to some 
extent to supply the local demand for building stone. Such openings 
are worked occasionally along various portions of Herring Run, near 
Hall Spring, and Ivy, and along the upper course of Gwynn's Falls, 
near McDonogh. These quarries furnish material similar to that 
obtained from those on Jones' Falls and Gwynn's Falls and help to 
supply the demand for paving blocks, sills, steps and curbings in their 
local areas. The chief sale for this product, however, arises from its 
use as a road ballast in the construction of many of the pikes which 
radiate from Baltimore. The material is crushed and furnishes a very 
fair road metal. 

GABBEO. 

Although the gahbro or " niggerhead rock " of Harford, Baltimore, 
and Howard counties is sharply separated from the granites and 
gneisses scientifically, when used as a foundation and building stone 
it competes with the granites and gneisses, so that it is proper to con- 
sider this material under the general title of the present division. 
The stone is so hard to work and so sombre in its effect, that little or 
no demand has ever been developed for it. There are, however, a 
few buildings such as the railroad station at Arlington, a church and 
some of the mills at Woodberry and a few scattered structures in the 
valley of the Patapsco which have been made of it. The stone is 
generally used in natural boulders, as the drift materials of the ISTew 
England states is used in the construction of higher grade of Queen 
Anne houses. The slight demand for dressed gabbro, the use of 
boulders and its plucky character have practically precluded the sue- 



MARYLAND GEOLOGICAL SURVEY 169 

cessfiil exploiting of this rock for building-stone purposes. There is, 
however, a strong and ever increasing demand for materials of this 
character in the construction of macadamized roads, since as a road 
metal there is no substance in the state better adapted for this pur- 
pose. 

AMPHIBOLE SCHIST. 

Carroll county, about Westminster, and Montgomery county, north- 
west of Washington, possess a finely crinkled, compact rock which has 
been used in a few instances as a building stone with good effect. 
The material qiiite probably is a metamorphosed amygdaloid, in 
which most of tlio minerals have been changed to very stable forms. 
It is of a pleasing grayish green color and even texture, and when 
freshly furnished it is very easily worked, being carved in almost any 
form with ordinary tools. On exposure it hardens through a secon- 
dary deposit of silica, and becomes a very serviceable stone. It has 
been used in the Iveyscr Memorial (^Imi'ch at Reistei'Stown, in the 
residence of the president of the Wcslei'ii Maryland College, and in 
the foundations of many of the more prominent buildings in West- 
minster. Some of the stone, which was used as a base of the build- 
ings constructed there at the beginning of the century, shows that it 
suffers little or no disintegration from exposure to the atmosphere. 
This material will never be used extensively as a building stone, since 
it is very imeven in its appearance and limited in its local occurrence. 
The porosity of its texture causes it to collect dirt rapidly and so it 
becomes unsightlj- if used in the large cities. 

Marbles and Limestones. 

The marbles and limestones of Maryland are the most uniformly 
distributed of all the building stones in the state, for larger or smaller 
areas may be found in Baltimore, Carroll, Howard, Frederick, Mont- 
gomery, AVashington, Allegany and Garrett counties. These differ 
widely however, in character, mode of occurrence and geological age. 
Unlike the granites, gneisses and serpentines, they are not confined 
to the central portion of the state, called the Piedmont Plateau, since 
they are found well developed in the broad Hagerstown and Frederick 



170 A HISTOEY OF THE QUAEEYING INDUSTEY" 

valleys and in the more mountainous areas of the AUeghanies. The 
exposures are almost always poor on account of the relative readiness 
with which these rocks break down under atmospheric agencies, and 
from the same cause they always occur in valleys and never along 
ridges or the crests of mountains, as the sandstones do. Moreover, 
whenever there occur sufhcient bodies the valleys are characteris- 
tically broad, ilat and very fertile. 

According to their geological age the marbles and limestones have 
midergone various degrees of change, since the time of their forma- 
tion. There is a progressive increase in their crystalline character 
and freedom from fossils, from the little changed fossiliferous Gi-reen- 
brier limestones of Garrett county to the crystalline, non-fossiliferous 
marbles of Baltimore county. This increased alteration, which they 
have imdergone, is accompanied by a change in color from the dark 
limestones of the Carboniferous and Lewistown formations through 
the lighter Shenandoah liiuestones to the variegated marbles of the 
Phyllite formation and the clear white or blue marbles of unknown 
age which are so extensively worked in Baltimore county. 

The a'coloaical frirmations which furnish either limestones or 
marbles are the 

Triassic (ISTewark), running as a narrow belt across Montgomery, 
Frederick and Carroll counties; 

Permian (Frostbiu-g), occurring in a few hills about Frostburg; 

Cai'boniferous (Bayard and Gi-eenbrier), forming several bands of 
limestone in Garrett and Allegany counties; 

Silurian (Lewistown), with its heavy beds of limestone in several 
belts confined to the western and eastern portions of the Central Ap- 
palachian district, in Allegany and Washington counties; 

Cambro-Silurian (Shenandoah), blue and gray limestones, dolo- 
mites and marbles, forming the broad and fertile Hagerstown and 
Frederick valleys in Washington and Frederick counties; 

Undetermined, interlocated in the phyllites of Frederick and Car- 
roll counties, and the 

Airhean (Algonkian '.) marbles of Baltimore and Howard counties. 

According to their character, their occurrence and the uses to 



MARYLAND rscni nniCAi ciirvfv 



vol IIMC M PI 4TF XIX. 




JlAUILA.Mi fiEOLOGICAL SURVEA' 171 

which these various stones are put they may be p-rouped for discus- 
sion in the following- snlidivisinns: 

The Marbles, includino- the hijihly crystalline dolomites and niariiles 
of "Baltimore, Howard and Carroll counties. 

" Potomac Marble " or breccia which is found locally in the " Tied 
beds" of the Newark Formation (Triassic) in Montponiory, Frederick 
and Carroll counties. 

Serpentines or ''Verde Avtiqve." of irart'ni'il. Italtiuidrc and 
Montgomery counties. 

The Limestones, including the crystalline blue and gray limestones, 
magnesian limestones and " dolomites " of Frederick, Washington, 
Allegany and (larrcft counties. 

MARBLES. 

The marbles of oMaryland have been known for their excellent 
eifect in building and nionumental work since the beginning of the 
century. They are all confined to that portion of ^Maryland com- 
posed of the highly crystalline rocks of the Piedmont Plateau, while 
those of economic importance at the present time are confined to a 
small valley known as the Green Spring Valley extending east and 
west at a distance of 12 to 20 miles north of Baltimore. 

This broad and beautiful valley sends off several large arms into 
the surrounding hills of gneiss and granite in such a way that the 
areal distribution is so anomalous and ii-regular as to render any ex- 
planation of the structure unsatisfactory. The same irregularity in 
distribiition is noticeable in the marble ai'eas between Glyndon and 
Glencoe and west of Ellicott City. This complexity of structure has 
led to \ai'i<>us views regarding the age of these deposits. Ducatel ' 
and Alexander from their study of the formation in 1833 regard 
them as " primitive." Tyson ' in his first i-eport classes them with 
the " metamorphic rocks " and evidently regards them as Silurian 
since they are placed on his map and in his list of " Geological For- 
mations " ° between the Chazy-Black River and Trenton. Tu the 

' Re])ni-t. on the Projt'<-ti'(l Survey of the State of .\Iaryl;ind. Annapolis, 
1834, p. lit. 

= First Report of Philii) T. Tyson. State Aui-icultnral Chemist [1800], p. :iO. 
" Same, pp. .iO, :io-.)G. 



I i'2 A HISTOKY OF THE QUAEEYING INDUSTBY 

" Eeport on the Building Stones " of the Tenth Census Mr. Hunt- 
ington ' describes the area as " a small isolated area of Lower Silu- 
rian limestone bounded by rocks of Archean Age," and calls atten- 
tion to the fact " that almost all of the marbles of commerce so ex- 
tensively quarried east of the AUeghanies are from strata of Lower 
Silurian Age." Somewhat later Dr. G. H. Williams who made a 
detailed study of the area expressed the conclusion that ' " The posi- 
tion to be assigned to this complex [gneiss, marble, quartz-schist] in 
the geological column is a matter deserving careful consideration, 
although data for a perfectly satisfactory conclusion are not at hand. 
It is believed that these rocks are demonstrably older than the altered 
lower Paleozoics of the western Piedmont region; and yet that they 
themselves contain in their chemical composition, stratigraphy and 
the presence of certain obscure conglomeratic beds near Washington, 
evidence of a clastic origin. For these reasons, as an expression of 
our present knowledge, the complex is pi-ovisionally assigned . . . 
to the Algonkian horizon." This view was subsequently restated ' 
and held by the author imtil his death. 

The marbles of this eastern area are throughout much coarser than 
the lenses of fine compact crystalline marble found intercalated in the 
phyllites of Carroll and Frederick counties. " Another striking con- 
trast between the marbles of these two regions is, that, while the latter 
contain tlieir impurities in the fonu of thin argillaceous bands, the 
former have theirs represented by layers of perfectly crystallized sili- 
cates." The western marbles also seem to be much more shattered 
and more difficidt to work than the somewhat uniformly jointed mar- 
bles of the Cockeysville area. 

Cockeysville and Texas. 

These two towns are located on the j^^orthern Central Railway about 
fifteen miles north of Baltimore, and are separated from each other 
by a distance of a mile and a half. Although situated so close to- 
gether, and representing but parts of a single formation in a common 

' Building- Stones and the Quarry Industry. Tenth Census, p. 177. 

■ Guide to Baltimore, p. 89. 

' Jfaryland. its Resources, Industries and Institutions, Baltimore, 1893. 



MAUYLAND GEOLOCJICAL SUKVEY 173 

valley, the quarries expose rocks showing many ditferenees in compo- 
sition, purity, coarseness of grain and texture, which have developed 
different industries in the two places. The rock at Texas is a coarse- 
grained marble of nearly pure carbonate of lime suitable for use as 
a flux or fertilizer, while that at Cockeysville is a finer-grained dolo- 
mitic marble, rich in magnesium and well adapted to l)nilding and 
decorative purposes. 

It is not known when the stone of this area was first used or first 
recognized as of economic importance. The first recorded description 
is that in a letter by Dr. II. H. Hayden ' to Dr. Nathaniel Potter 
in which he writes: "Immediately to the northward, as well as to 
the eastward of the Hare Hills the limestone commences. This, I 
believe, is its first appearance in the vicinity of Baltimore, which is 
distant six miles. From this to the distance of twenty miles to the 
northward, and how much farther I am unacquainted, the limestone 
tracts discover a variety of transitions. In many places it approaches 
so near to a marble, as to render it not only useful, but highly valuable 
in almost every branch of civil architecture; and the prospect is favor- 
able to a supply of such as will answer every purpose of statuary and 
sculpture in all their variety." 

That Dr. Hayden's view of the adaptability was correct was soon 
shown by .\[r. Mills in the construction of the Washington Monii- 
ment in Baltimore, the cornerstone of which was laid on the Fourth 
of July, ISl."). A lack of funds delayed tlio completion of the monu- 
ment for nearly fifteen years, and it was not until the 25th of No- 
vember, 18:29, that the last piece of the statue, comprising the bust, 
etc., was raised to the summit. 

The three blocks constituting the figure of Washington wei-e origi- 
nally quarried as a single piece over seventeen feet long at the Taylor 
quarry, about a quarter of a mile west of the railroad at Cockeysville, 
and presented by F. T. D. Taylor of Baltimore county. The marble 
used in the moniuueut, which came in part from tlie Taylor ([uarry 
and in part from the Scott quarries five miles fartlici- north, was 

' Hayden's Geological Sketch of Baltimore. Jour. Balto. Med. & I'hil. Lye. 
vol. i, ISll, pp. 255-271. Repub. Bruce's .Xmer. Min. Jour., vol. i, New York, 
1S14, pp. 243-248. 



1 I 4 A HISTORY OF THE QUAEEYIXG I>-DUSTEY 

donated by General Charles Ridgely of Hampton, and the stonc- 
eutting was perfoi-med by General William Stenart.' 

After this increased demand for marble as a building stone, it is 
doubtful if much material was taken out for \ise in structural work 
during the succeeding iifteen years; the trade in lime for agi*ieultural 
purposes, however, increased rapidly diu'ing the years following the 
war of 1812, until it was estimated that fully 200,000 bushels were 
produced annually. This trade was so extensive, that in 1S39 there 
were fears expressed that the old cpiarries were nearly exhausted. 
The popular apprehensions became so great that the State Geologist, 
J. T. Ducatel, made an investigation which showed the practically 
inexhaustible character of the deposits. The same year (1839) Mr. 
Gilmore ' offered to furnish stone to the Federal Government at 90 
cents per cubic foot. 

From this same rejDort (1830) we gain the first information con- 
cerning the operators in this region in the statement that " the quarry 
on the lands of Mr. "\Vm. Bosley has been worked for many years 
past by Messrs. Baker and Connolly." The senior member of this 
firm was one of the first owners of this marble property and he did 
much to develo]) the industr\\ Sometime in the early forties !Mr. 
Baker associated with him in the business his son-in-law James B. 
Connolly, who succeeded to the business on the death of Mr. Baker. 

The fullest accoimt we have of the early woi'kings of the area is 
that given by Dr. David D. Owen ' to the Building Committee of 
the Smithsonian Institution after his visit to the quarries in the early 
part of 1847. He foiind at the time some thirteen quarries in moder- 
ately active operation, the product being used for both building and 
agricultural piu'poses. 

Five operators, Messrs. Samuel Worthington, Griscom and Bur- 
roughs, Fell and Robinson, E. J. Cooper and Thos. Symington, made 
bids for furnishing the stone for the Smithsonian Building without 
success The stone at that time was offered at $1.87 to $2.20 per 

' Scharf's History of Baltimore City and County, Maryland. Phila., 1881, 
pp. 265-267. 

-Ex. Sen. Doo.. 3.ith Cong., vol. v. >'o. :i21. 

= Sen. Doc. .KiTli Cong-.. 1 Sess., lYo. 2.3, pp. 25-30. 



-MAIiVLAXD IIEOLOCKAL .SliaKY ll O 

porch of 3000 pounds for niLlilo delivcrpcl free on board tlie c-ai's at 
(.'ockeysville. 

Of the qnarries inspected \>\ Dr. Owen uiAy a few arc still (IS'J.SJ 
in operation, most of them liavinu- Ijecome exhausted. 

Scott's qnarrv, which is located about five miles ndiib nf ('ockeys- 
ville, has nt)t been worked dnrinji' the last forty years, as the openini>- 
was abandoned as soou as the good stock was exhausted, it was from 
this quarry that part of the marble for the Wa.shing-ton monument 
was obtained. 

An old quarry formerly on the jiroperty of Mrs. Chisilla Owings, 
about 200 yards from the present Beaver Dam quarries, was opened 
in 1840 and worked till 1873. It was then ai)andoned on account 
of the poor ciuality of the stone, and is now filled with water. This 
quarry was operated for a time by the Sherwood Marble Co. 

The old quarry of Thos. Worthington from which the stone was 
obtained for the City Hall in Baltimore is situated about a mile west 
of the railroad at Cockeysville Station. It was opened some years 
prior to 1845 and was abandoned in 1873, when the white stone was 
exhausted. It is now the property of Mr. William Wight. 

Samuel Worthington's old quarry is located about half a mile 
southwest of the one just mentioned, aud is now owned by ^Ir. E. 
Gittings Men-yman. It was abandoned in 1873 on account <if the 
poor quality of the stone. While in operation the stone was quarried 
only when orders were received for it. 

A quarry now owned by Mr. Lenwood Parks is situated about a 
quarter of a mile west of the last mentioned cjuarry. It was opened 
originally by Charlotte Owings and has not been operated since 1855. 
It was worked only according to orders and the good stone was soon 
exhausted. 

Another old quarry about a quarter of a mile north of Cockeysville 
on the property of ilr. Geo. Jessups was formerly operated by a ^Ir. 
Cockey. It was shut down about 1879, since it was impossible to 
get oiit stone of snfticiently high grade to compete with the product 
of the other quarries. 

From the foregoing it is seen that the present quarries, operated 



ITC! A HISTOEV OF THE QUAEKYING INDUSTRY 

by the Beaver Dam Marble Co., have surpassed and outlived the 
competing quarries by the greater abundance and higher quality of 
the marketable stone. This company owns and operates the old 
Baker and Connelly quarry, which on the death of the senior partner 
was operated by Mr. Jas. B. Connelly, who left it to his sons Messrs. 
J. B. and T. F. Connelly. It was during the years 1859-61 that 
the huge bloclvs, each 26 feet in length, were furnished for the 108 
columns in the National Capitol. These quarries were finally pur- 
chased by the present Beaver Dam Marble Co., capitalized at $100,- 
000. It began operations in 1879 with Mr. Hugh Sisson as presi- 
dent. To-day this is the only large operator at Cockeysville and at 
the time of writing it is busy fiirnishing material for the new Court 
House in Baltimore. It has already commenced the shipment of 38 
ton monoliths which are to be used as columns. (See Plate XXII, 
Fig. 1.) 

There are more of the old quarries still active in Texas than in 
Cockeysville, although little or nothing is done in quarrying stone 
for building purposes. 

The Fell and Robinson quarry which was opened early in the cen- 
tury is situated a short distance west of the railroad. It passed from 
the hands of the original owners to a Mr. Miller, and from him to 
Mr. V. T. Shipley, whose heirs are now operating it. All the stone 
quarried is burnt in a single kiln which uses about 10 tons of stone 
daily. 

Griscom's old quarry is on the east side of the railroad about 400 
yards from the preceding. It is owned and operated by Mr. Wm. P. 
Lindsay, who employs about 30 men. Work is carried on all the 
year roimd, six kilns burning each day a load of about fifteen tons of 
stone apiece. 

Burroughs' quarry is on the west side of the track and is now 
owned and operated by Yellott and Kidd, who bum about ten tons 
of stone each day. 

Mr. William C. Dittmann operates the following old quarries: 
Mrs. Chisella Owings', situated on the property of Miss M. B. Price 
about a mile northeast of Texas and half a mile east of the railroad; 



MARYLAND GEOLOGICAL SURVEY 177 

Cooper's q\iarrv on the same property immediately on the railroad ; 
the old John C Bosley quarry at Texas and the Parks quarry, once 
operated by the Ideal Lime Co. Ten kilns are kept going through- 
out the year, fonsuming- in all about 120 tons a day. It was from 
the old Bosley quarry that the stone in the N^orth Avenue viaduct at 
Baltimore was obtained. 

The Texas Lime Co. has a quarry at Texas which produces about 
10 tons of stone daily. 

Mr. Frank Lee has a quarry on his property about half a mile north- 
east of Texas wliich is worked throughout the year, prodiieing about 
10 tons of stone each day. The entire product is burnt and sent to 
the Baltimore chrome works, where it is used as a flux. 

The texture of the eastern marble varies widely. The rock from 
Texas is a very coarsely crystalline marble or " alum stone '' in which 
the individiial grains are sometimes -^ or f of an inch in diameter. 
The constituents are weak in themselves and they are weakly held 
together. The single grains show tmnning striae parallel to the crys- 
tal —J E that liave been prodviced by a pressure, causing a gliding of 
the molecules over one another which has weakened the strength of 
the grain. Such a texture as is here shown renders the rock nearly 
worthless as a building stone where small blocks must be used and 
great weights sustained. This is emphasized by the determination of 
the crashing strength, which is very low. The gi-ain of the Cockeys- 
ville or Beaver Dam rock is fine, the individiials seldom exceeding r? 
of an inch in diameter, the eomiionent particles fonning a closely 
interlocking aggregate. This interlocking of the grains tends to 
produce a more compact and harder rock whose crushing strength 
is lugh (67,000 lbs.) and absorption ratio low (0.213^). This differ- 
ence in closeness of grain is not strictly a geographical one, since fine- 
grained marbles, similar to those at Cockeysville, may be found at 
Texas. There is at the latter point, however, little evidence of the 
occurrence of rock which will combine such fineness and closeness of 
grain, freedom from mica and pyrite, and abundance as is shown in 
the rock worked by the Beaver Dam Company at Cockeysville. 

The uniformity in color is more marked at Texas than at Cockeys- 

12 



l'J'8 A mSTOET OF THE QTTAREYING IHDTJSTRT 

ville, where there are frequent zones or horizontal bands of crystal- 
lized silicates, which represent old impurities and possibly the original 
bedding of the rock. These darker bands which are composed of 
copper-colored mica (phlogopite), colorless, radiating tremolite, pyrite 
and quartz, sometimes obstruct the working of the quarries when the 
stone required must be large and cannot be stood " on edge." In the 
smaller blocks these bands are avoided by " facing " parallel to them 
and setting the blocks perpendicular to their natural bedding. I^ni- 
formity in the size of the grains and in the texture, on the other hand, 
are more prominent at Cockeysville than at Texas. This uniformity 
in texture distributes the strain more evenly, making the positir,n 
" on bed " and " on edge " less essential.' 

The color of the marketable Cockeysville rock is clear white,= with 
now and then a few streaks or bands of pale blue which give to the 
rock face a faint gray color. In the poorer grades of stone which 
are sometimes shipped as far as Baltimore for use as door steps, sills, 
etc., there are occasional brown bands where the mica has been more 
abundantly developed. When polished and kept clean the rock is 
of a dazzling whiteness, often noticed by visitors walking through 
the residence portion of Baltimore. If the rock is laid in ashlar the 
little interstices between the grains soon gather dust, and the bright 
effect of the white rock is softened to a dove-colored gray. This same 
toning effect may be noticed in buildings, like the Peabody Institute, 
Baltimore, which have been built of smoothed stone, that has not 
been scraped or xepolished. ' The Cockeysville stone is thought by 
some to stain easily, but this f aiJt may be avoided by carefully select- 
ing for first-class work those pieces which are free from the pyrite 
that sometimes is present in little pockets or stringers. Few instances, 

^ After examining- a large number of buildings where f'^/l'^^l'Z 
been used as a trimming and set " on edge." the wri er is --l-^d to b^ leve 
that the texture is sntfieiently massive and granular to warrant such a 
setting, where the weight and exposure are not exceptionally l^^ge. This 
view seems to be borne out by the various results of pressure tests to which 
the rock has been subjected. , ^, ^ t ,11 

= The accompanying illustration (Plate XXI) hardly does the stone full 
justice since it fails to give the clear white color that is so characteristic 
for the stone. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXI, 




MARBLE. 

COCKEVSVll.LK, HAl.TIMORE lOlNlY. 



MARYLAND GEOLOGICAL SURVEY 179 

in the buildings examined, have sliown anv indication of staining 
from inherent impurities. 

The Texas and Cockeysville stones differ in their chemical compo- 
sition as well as in their texture and color. Although before IS.iO 
there was some dispute as to which of the two rocks was richer in mag- 
nesium the question is now clearly decided. According to Williams 
" the long series of analyses which are constantly being made of the 
Texas rock by the IMaryland Steel Company, where it is used as a 
flux, show that it docs not average over five per cent, of carbonate of 
magnesia; a niunber of analyses of the Beaver Uam product, on the 
other hand, give the average amount of this substance as high as forty 



cent. 


;> 1 




















Analf/ses of Ma, 


Mr. 












I. 


11. 


111. 




IV. 




IllSoI. 




h.'tl 




2. 33 




2.00 




SiO, 






0.44 










A 1,0, 
Fe,0, 
FeO 


I 
) 


.40 


tr. 










C:iO 




29. OS 


30.73 


29.30 




.52.08 




MtrO 




20. SO 


20.87 


20.81 




2.38 




HO 






1.22 


0.08 








CO., 




44.26 


45.85 
100.33 


4.5.31 




43.54 




itO.Ol 


99.38 


100.00 




Specimen. 




Analyst. 






Ueferenceg. 


I. 


Cookeysvi 


lie. 


SclnieHler. 




Bull., 


148, 


. p. 25.5. 


II. 


„ 




Whittiehl. 




" 


60, 


p. 2.55. 
, p. 159. 




" 




" 




(iiiide 


to Baltimore, p. 08. 


III. 






Hiffgins. 


(n 






( reralculated.) 



IV. Texas. estimated averaire. 

The exact limits of the arcal distribution of the marble and the dolo- 
mite have never been determined because of the lack of exposures 
and the high state of cultivation throughoiuit the area underlain by the 
two rocks. It seems probable, from the data at hand that the distri- 
bution presents an intricate interweaving of the two types which may 
yield much information on the subject of dolomitization if the work- 
ings ever present sufficiently continuous exposures of the rock surface. 

' Mai_vlam.l, its Kesources, Industries, and Institutions, p. 135. 



180 A HISTORY OF THE QUAKRYING INDUSTRY 

The microscopical texture of the Cockeysville and Texas rocks dif- 
fers but slightly from that presented to the unaided eye. The grains 
interlock in about the same Avay and the interstitial areas left between 
them seem very small. The two rocks differ from each other, when 
seen with polarized light, since sections of the Cockeysville rock show 
fewer vari-colored bands than that from Texas, due to the secondary 
twinning of the small individuals of the carbonate of lime which is 
more susceptible to twinning through pressure than the magnesian 
carbonate. The two minerals are intimately mixed in their distribu- 
tion, and only occasionally show any marked variation in the size of 
the grains. Accessory minerals are present, but they show no differ- 
ences in texture beyond those evident to the naked eye. 

Few American building stones have been as thoroughly investigated 
with reference to their crushing strength as the marbles of Baltimore 
county. From the time that Mr. Kobt. Mills became interested in 
the properties of the Baltimore marbles, which he used in the con- 
struction of the Washington monument in Baltimore, the engineers 
and architects charged with the construction of the Public Buildings 
in Washington have watched with interest the behavior of this stone 
in structures. The use of these marbles in public buildings has also 
led to extended experiments on the part of government officials. 
Prior to 1837 all of the important public buildings at Washington 
were constructed of Aquia Creek (Va.) sandstone, which was so 
treacherous and unsightly after exposure that as early as 1839 an 
inquiry was instituted by Congress as to the availability and cost of 
marble and granite. At this time Mr. Gilmore offered to furnish 
marble from the Baltimore county quarries at 90 cents a cubic foot, 
and Mr. Mills, the government architect, highly endorsed the rock. 

The iirst published results of crushing strength tests on Maryland 
marbles were obtained before 1851, as stated in Professor W. R. 
Johnson's paper on American and Foreign Building Stones (pp. 6, 
7),' by Mr. Eobert Mills and Dr. Charles G. Page. These tests were 
made on two-inch cubes of coarse '' alum stone " from Texas and 

' Comparison of E.xperiment.s on American and Foreign Building- Stones 
to determine their relative strength and durability; by Professor \Valter R. 
Johnson, Amer. Jour. Sci., 2 ser., vol. xi, 1S51, pp. 6-7. 



MARYLAND GEOLOGICAL SURVEY 181 

showed considerable range in values. Similar tests were also made 
on two-inch cubes of fine grained marble from Symington's quarry 
(now abandoned), which show much greater uniformity. Other ex- 
periments on Maryland marbles were made by Mr. Dougherty, Su- 
perintendent of the Washington monument in Washington, which 
gave still other results. Prof. Johnson noted the wide discrepancies 
in the figures obtained from these different experiments on material 
from the same localities, and concluded that the variations miist be 
explained either on one or the other of three suppositions; 1st, that 
the strength of the different specimens of the rock is thus variable, 
and that consequently no certain reliance can be placed on its powers 
of resistance; 2nd, that the experimenting or the machine^ with 
which the testings were conducted were faulty; or 3rd, that the re- 
sistance to crushing for a imit of area at the ba?e, increases in some 
ratio with the number of units composing that area, that is, with 
the actual area of the base.' Johnson favored the third explanation, 
but the second seems to be as much in accord with later results. Since 
these early experiments were conducted, great advances have been 
made in the manner, uniformity and accuracy of the testings, so that 
residts obtained now are not to be compared or averaged with those of 
earlier M'orkers. The conditions under which the testings are carried 
on cause the results to vary within wide limits. 

The experiments conducted in the preparation of the present re- 
port were made with the greatest care and under the same conditions. 
All of the specimens were two inch cubes, placed between two 
quarter-inch thick soft pine blocks in exactly the same position, and 
the testing machine was run at the same speed in each case. Almost 
all of the blocks were cut from the average stock of a well-known 
stone-yard. Some were crushed just as they were received from the 
stone cutter, while others were crushed after they had been submitted 
to absorption, freezing and thawing tests. 

The results are as follows: 

Crack. Bresk. 

L CockeysviUe iiuirhli', unoricnted without immersion .57,740 

•i. •• ■• •• •• " SI. .580 

3. - •■ .. .Ufter absorption j 

( and freezinir. ) 

4. •• " " •• •■ ■ -ir.rM) (i'.i.soo 

• Loc. eit., p. 17. 



]82 A HISTORY OF THE QUARRYING INDUSTRY' 

Somewhat higher ligures have been obtained at other times, as is 
shown by the accompanying letter, but the conditions of the testing 
are mjt known. 

[Hugh Sisson, Esq., 
Baltimore, Md., 

giy ■ 1 Washington, D. C. [ ] 

The compressive strength of the six 3" cubes of Beaver Dam Marble, which you 
furnished, was as follows: 

No. 1. 84,000 lbs. 
3. 90,000 
3. 90,000 
i. 84,000 
.5, 0.5,000 
6. 94,000 



89,066 Average. 

Strength per square inch, 33,416 lbs. The strength of the large crystal marble is 
about 13 600 lbs. per sq. inch. The 1" cubes have not yet been crushed, but I feel 
satisfied the result will not show a greater strength per square inch than those 
obtained in crushing 3" cubes. 

Very respectfully, 

Your Obt. Servt., 

Geo. W. Davies, 

^ „ , „ „„ Cifpt. Axxixt. EM/ineer. 

By direction of Col. Casey. i" 

It is therefore clearly shown that the rock from the Beaver Dam 
quarries at CockeysviUe, as usually furnished, can well sustain any 
weight which the exigencies of structures may demand. 

Many crushing tests were made on the coarse-grained " alum stone " 
from Texas in earlier years and the results have been brought to- 
gether by Johnson. The most satisfactory test, however, is furnished 
by the Washington National Monument itself, which shows the 
Texas rock (Griscom's lime riuarries) subjected to increasing pressure 
from top to bottom as given in the following table from the report 
made bv Col. Thomas L. Casey, Corps of Engineers, Fnited States 
Army, engineer in charge of the construction of the monument, to 
W. W. Corcoran, Esq., chairman of the joint ^commission lur the 
completion of this structure dated July 37, 1878.' 

^Quoted in Tenth Census, vol. x, Report on Building Stones, p. 359. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II. PLATE XXII. 




Vu:. l.-TIIlin'Y-KK'.irr T(l\ MdXnl.rni. cncHKYSVILLK. 




I'u;. L'.-lHnoMAG .M.VKlil.K (jr.MMIY. I'nlXT OF HOCKS. 



ilAKVLAXD GEOLOGICAL SURVEY 



183 



Distance of 
Joint from 
top. tn feet. 

2.5 
.50 


Contents In 
cutilc feet. 






Average wetglit per cubic foot of 
masonry in severai divisions. 


13 


555 












100 


34 


719 






First Division, 169.5 


lounds. 


150 


63,957 












171.00 


79 


239 












200 


101,674 












250 
300 


148 
204 


298 
373 






Second division, 167.8 


pounds. 


343.00 


261 


291 












3.50 


272 


369 












400 
450 


360.268 
470,495 






Tliird division, 16.5.8 pounds. 


.500 


585 


476 












Weight In 
pounds. 


Pressure In tc 
squB 


n 
re 


(2210 lbs.) per 
foot. 


Distance of Stability 
line of under 
resistance from action of 
axis in feet. the wind. 


Least. 


.M 


etin. 


Greatest. 














0.603 


29.4.54 


2,297,630 


2.67 




2 


90 


3.26 


1.0.52 


17.378 


5,8.S4,973 


4.41 




5 


23 


0.04 


1.670 


11. .539 


10,840,728 


5.85 




7 


24 


S.04 


2.087 


9.7.58 


13,431,081 


6.44 




s.os 


9, 72 


2.224 


9.360 


17,195,713 


7.14 




9 


12 


11.09 


2.383 


8.983 


2.5,019,140 


8.35 




0.90 


13.44 


2.007 


8.610 


34,411,997 


9.54 




2 


63 


1.5.73 


2.779 


8.4.52 


43,963,6.55 


10.. 56 




-1 


11 


17.60 


2.899 


8.417 


4.5,816,912 


8.28 




1 


51 


14.73 


2.892 


8.481 


61,38.5,397 


10.09 




3.. 84 


17.60 


2.869 


8.902 


78,666,278 


11.76 




0.03 


20.30 


2.889 


9.190 


97,264,244 


13.38 




8.02 


22.6.58 


2.928 


9,413 



The fact that tlie coarse-grained marble without crushing actually 
withstands a prcf^ure of 28,790 ' pounds to the square inch when this 
pressure is applied evenly and slowly would seem to indicate that 
stone like that from Cockeysville might withstand under similar cir- 
cumstances a pressure of fully twice as iniicli as tlie figures given, 
since the earlier tests by Mills and by Dougherty place the strength 
of the " Symington " stone at twice that of the Texas rock. 

The freezing tests which were conducted by Dr. Charles G. Page 
according to the Brard method described on page 104 gave the fol- 
lowino- results: " 



' Computed on tlie assumption that the value of the crnshing weight varies 
as the third power of the side of the areas compared. 

'Report of the Board of Regents of the Smithsonian Institution. Sen. 
Doc. No. 2.'!, 30th Conoress. 1st Session, p. 21. 



184 



A HISTOKY OF THE QUAKRYING INDUSTRY 



Spec, marked. 


s. G. 


Weight 
cubic ft. 


Loss 

frost 

in 
grains. 


l-er- 

cent. 

of 

loss. 


'i. bymington's close-grained marble 










(similar to Worthington's.) 


3.834 


177.1 


0.20 


(I.02B 


4. " large crystal marble, 


2.8.57 


178. .5 


0. .50 


0.069 


o. •' blue limestone, 


2.613 


163.3 


0.34 




s. Port Deposit granite, 


2.000 


103.0 


5. 0.5 





Since the cubes vised were but one inch in diameter they did not 
weigh over 720 grains and the percentage approximates the values 
given in the fourth column. 

During the preparation of the present report Mr. Shellenberger 
tested the rock by depositing two-inch cubes in a freezing chamber 
for forty-eight hours and subsequently drying them at 212° F. The 
percentage loss from freezing and thawing, calculated on the differ- 
ence between the original weights before immersion and after drying, 
was obtained as follows: 











Weight 














after 














freezing 














48 hours 














ata° F. 




Per cen t 






"iVi-ight 


Weiglit 


and then 




of loss 






alter 


l)efore 


dried at 




by 






drying 


freezing 


312° F. 




treezing 


Mark on 


Kind of 


24 iiours 


48 hours 


for 24 


Loss in 


and 


cube. 


stone. 


at iVi" F. 


at 2^ F. 


hours. 


weight. 


thawing 






Grams. 


Grams, 


Grams. 


Grs. 




3. 


Marble 


367.15 


367.93 


367.13 


0.02 


0.005 


4. 


.' 


3li7.07 


367.86 


367.03 


0. 04 


0.11 



These figures and practical experiments show that a cubic foot of 
the Cockeysville rock weighs about 175 pounds per cubic foot or 
4,375 pounds per perch of twenty-five cubic feet.' They also indi- 
cate that the close-grained marble (now the only one in general use 
for buildings) is exceptionally non-absorbent and resistant to the dis- 
integrating effect of frost. This is well borne out by a study of the 
oldest structures standing, which show little or no " spalling " as the 
result of frost action, and the character of the weathering shown in 
the quarries. 

The " dry seams " which have caused occasional loss, as in the case 
of the Baltimore Court House monoliths, seldom prove troublesome 
in the material furnished for ordinar\' buildings, since they may 

' When sold by weight it has been customary to figure 3,000 lbs. to a 
perch. i, 



SIAEYLAXD GEOLOGICAL SUKVEV 185 

usually be avoided in the smaller blocks. The strain which cause 
them to open after dressing is also more evenly di^tribnled in struc- 
tures using smaller pieces of stone. 

The mineralogical and chemical composition of carefully selected 
blocks of marble from Cockeysville show that little more can be de- 
sired to assure the stability and consequent durability of the stone. 
When care is taken to avoid the few bands and pockets of pyrite and 
mica there is nothing in this rock which will render its decomposition 
rapid, as all the accidental or accessory constituents are in the form 
of stable compounds such as tremolite, tourmaline, or quartz. These 
in the first-class stock are seldom in any abundance, with 'occasional 
exception of finely fibrous and disseminated colorless tremolite. The 
outcrops, though decayed from ten to twenty feet below the surface, 
show the rock to be very durable for a carbonate, especially as the cn- 
tii'e area of its occurrence has been exposed more or less continuously 
to disintegrating influences since at least late Tertiary time without 
any period of scouring by glaciers. Old tombstones, said to have 
been cut as early as 1829, show their lines as sharp and their surface 
as smooth as pieces which have been exposed to the atmosphere for 
only a few years. Little discoloration has developed beyond the 
darkening due to dust or nearby brick or iron. 

The other areas of marble, similar to that of the Green Spring 
Valley, are not worked for building stone, but the whole product is 
burnt for lime, which is generally applied to the land of the imme- 
diately adjacent country. The centers of distribution arc Rutler in 
Baltimore county; Marriottsville and Highland in Howard county. 
Both Butler and Highland are so far from railroads and so lacking 
in transportation facilities, that they will never compete with tiic 
Cockeysville product so long as conditions remain as at present. 

Marbles of Carroll County. 

Intermediate between the clear white, fine grained saccharoidal 
marbles of Baltimore and Howard counties and the crystalline dark 
blue and gray limestones of the Hagerstown and Frederick valleys 
are the variegated marbles of Carroll county, which have fui-nishcd 
samples imsurpasscd in beauty and variety by those of other states. 



ISCl A HISTORY OF THE QUAEKYING INDUSTRY 

At the Centennial Exposition in Philadelphia in 1876 there were ex- 
hibited specimens of " deep red," '' dark red veined with white," 
" salmon colored," " lavender veined," " undulate pink and white " 
and " rnhy " marbles which came from ( 'arroU and Frederick counties. 
Besides these many others might have been supplied. Some samples 
of tlie stone resemble the deeper colored Tennessee marbles, while 
others suggest the yellow Sienna, but lack its bright, clear tone. 

All of these varieties occur in lenses in the phyllites which in cer- 
tain localities have been shown by Mr. Keith to be of Cambrian age. 
The lenses do not occupy any considerable extent or present large 
exposures, but instead are confined to valleys which are long and nar- 
row and arc the direct result of the readier removal of the calcareous 
rocks than of the adjacent shales and sandstones. The marbles thus 
occupy the bottom lauds and seldom outcroj) high above the level of 
the streams. All of the valleys fonned in this way trend parallel to the 
longer axes of the lenses in a X. E.-S. W. direction, as is well rep- 
resented in the valley east nf the road from T^ew Windsor to Union- 
ville and in the smaller valleys at the south of Spring ]\Iills P. O. 

Up to the present time the method of extracting the stone has been 
very crude, since the only desire has been to obtain the rock in pieces 
small enough for foundations and ordinary buildings. According to 
information furnished by Prof. Uhler, there has been a marked de- 
terioration in the method of (luarrying these marbles since he first 
began to study these rocks. Formerly considerable attention was 
paid to the extraction of the stone without explosives, while at the 
present almost all of the quarries use powder or dynamite to loosen 
the rock and render its extraction easy. During the earlier workings 
beautiful slabs were taken out for altar fronts and interior decorations. 
From a study of the walls of the small quarries it seems probable that 
no blocks can now be obtained in size, shape and quantity for first-class 
building purposes. The jointing is not trustworthy and the rock 
tends to break down into thick angular blocks varying in size from 
eight cubic feet to small fragments. Careful work with channelling- 
niachines or diamond drills and a discontinuance of explosives might 
allow the quarrying of blocks which would be valuable for interior 
decoration in the form of mosaics and mantels. 



MARYLAND GEOLOCIC AI. Sri;\-KV 187 

Another serious drawliiu-k in working these rocks, wliicli iqipear so 
beautiful in samples, is the iircfiiilar distrii)utioii of the ^Milurs, which 
seem to oliev no nile and to follow no definite eonrse. Tlie white 
may be i-i'iihii-i'(l by red uv the red may be nqihiccd by liluc and sn dm. 
There seems, iidwevcr, to be a greater amount of red and white or 
clear white tiian anyfliinf>- else. The variations in color are so fre- 
([uent and uncertain, that it seems doubtful, if any quarry now opened 
could fultill any niodcnitcly biri;c (irdrr wilb niatiTial like a ijiven 
sample. I'bai llurc arc beautiful uiarbb's within these lenses is be- 
yond doubt, but a suitalde ]ilace for tiic d('\ilii]iniont of a jn'ofitable 
inthistry in I hem has yet to be found. 

Amoui;- the o]ienin,4i's in tiiesc marbles in Carroll county, wliiidi are 
used quite iicncrally for lime, are the following: 

Jonas Batdiman, Bachman's Mills; "Wm. H. Eberhart, Bachman's 
.Mills; .Terenu'ah Ih'own. Xew AA'indsor; Samucd Harris, Lessee, Xew 
Windsor: V.\>\\. Stoufl'cr, Xi'w Windsor: John T. Dutterer, Silver 
Run: W'ni. A. Leppo, Silver Hun; J. C. Robertson, Warfieldsburg 
I'. ().; E. J. Gorsuch, AVestminsfer; Wm. A. Boop, Westminster: 
Henry B. Rigle, Westminster. 

At various points around the northern end of the Blue Bidge and 
occasionally along the course of the Shenandoah river Mr. Keith has 
found a local development of white marble, which is often pure white, 
with an exceptionally even grain, resend>ling a high grade statuary 
marble. .Mention of such material may be found in the reports of 
the earlier state geologists, and the exposures have been met with in 
several places, hut in no instance have they been free from stain or 
jointing in masses which offer a reasonable return for investment. 
Such, however, may .sometime be found, although Keith eonsidei-s 
that this marble is not of sufficient body to be valuable. Small quar- 
ries have been opened near Keedysville and just below the station at 
Edgemont, but these have not been adequately developed. 

POTOMAC MAKBLE. 

The most interesting building material in the entire state of ^Fary- 
land is the " Potomac marble,"' " calico rock " or '" Potomac breccia," 
wliicli has bi'cu used occasionally for the greater portion of the cen- 



188 A HISTOKY OF THE QUAERYI>-G INDUSTRY 

tnry. The chief interest in this rock arises from the fact that it is 
" the only tnie conglomerate or Ijreccia marble that has ever been 
utilized to any extent in the United States." ' 

This conglomerate is fonnd in several places along the eastern slope 
of the Bine Eidge and is most extensively quarried in the vicinity of 
Point of Eocks, Frederick conntv near Washington Junction on the 
Baltimore and Ohio Railroad. The quarries are small affairs, which 
have been operated spasmodically. The one in operation at the pres- 
ent time is located about a mile east of the Washington Junction sta- 
tion on a spur which runs northeasterly from the Metropolitan 
Branch. 

This rock was first brought into notice by Mr. B. H. Latrobe, Su- 
perintending Architect in the construction and repair of the Capitol 
and White House before and after the war of 1812. In his report 
on the piiblic buildings, read February 14, 1817,' Mr. Latrobe gives 
the first account of the use of this marble as a building stone, as fol- 
lows: " For the columns, and for various other parts of the Hoiise 
of Representatives, no free-stone that could be at all admitted has 
been discovered. Other resources, therefore, were sought after. A 
stone hitherto considered only as an enciimberance to agriculture, 
which exists in inexhaustible quantity at the foot of the most south- 
easterly range of our Atlantic mountains — probably along the great- 
est part of their extent, but certainly from the Roanoke to the Schuyl- 
kill, and which the present surveyor of the capitol, and probably oth- 
ers, had many years ago discovered to be a very hard, but beautiful 
marble — this stone was examined, and, after much labor and perse- 
verance, has been proved to answer every expectation that was formed, 
not only of its beauty, but of its capacity to furnish columns of any 
length, and to be applicable to every purpose to which colored marble 
can be applied. 

■■ The present commissioner of public buildings has, therefore, en- 
tered intii a contract for all the columns, and pi-ogress has been made 
in quarrying them. They may be procured each in a single block 
sliould the transportation be found convenient. 

' Merrill, " Stones for Building- and Decoration," New York, John Wiley 
and Sons, 1S91. p. 92. 

-Senate Documents, 14th Congress, 2nd Session, Xo. 101, pp. ?, and G. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXlll. 




r-OTOMAC MARHl.E. 

rolNl OF RUCKS. KKKDERU K lOL'NTV. 



^t.\RYLA^D GEOLOGICAL SURVEY' ISO 

" A block of one of the pilasters lies ready to be brought down to 
Washiiiiiton, and will, probably, arrive in a few days. The quarries 
are situated in Loudoun county, Virginia, and Montgomery eountj', 
Maryland." 

The columns which were then procured are still standing in the old 
House of Rpjjresentatives, now iised for the sittings of the Supreme 
Court. The quarries whence they were obtained have never been 
fully developed, although Mr. Latrobe thought that he had found in 
the newly discovered marble of the Potomac an inexhaustible I'esource 
of the most beautifid building materials situated easily accessible by 
water. There is some doubt as to the exact location of the particttlar 
source of these blocks used in the capitol, although they were mono- 
liths of considerable size for the lime and tiie primitive means of trans- 
portation. 

Plate .\.\I1, Fig. -2, represents tlie opening reported to be the 
source. It is situated in the woods north of the Metropolitan Branch 
of the Baltimore and Ohio Railroad about half way from "Wash- 
ington Junction to the quames now in active operation. 

A few yeai'^ later in his paper on the geology of the Southern 
States the Rev. Elias Cornelius ' gives the following account of this 
brecciated limestone: 

" It is also in the valley of this river [Potomac], and not far from 
its famous passage through the Blue Ridge, that immense quarries of 
beautiful breccia have been opened. This rock was first brought into 
use by Mr. Latrobe, for some years employed liy the government as 
principal architect. It is composed of pebbles, and fragments of 
siliceous and calcareous stones of almost every size, from a grain, to 
several inches in diameter, strongly and perfectly cemented. Some 
are angular, others rounded. Their colors are very various, and often 
bright. Red, white, brown, gray, and green, are alternately conspicti- 
ous with every intermediate shade. Owing to the silicious stones 
which are frequently imbedded through the mass, it is wrought with 

' Ou the Geology, Mineralogy, Scenerj', and Curiosities of I'arts o£ \'ir- 
g-inia, Tennessee, and the Alabama and ilississippi Territories, &c., with 
Miscellaneous Eemarks, in a letter to the Editor, vol. i, Amer. Jour. Sci., 
New Haven, 1819, p. 216. 



190 A HISTORY OF THE QUAEEYISG ISDUSTRY 

much (lifficnlty; bnt Avlien finished, shows a fine polish, and is unques- 
tionably one of the most beautifully variegated marbles, that ever 
ornamented any place. It would be difiicult to conceive of anything 
more grand than the Hall of the Representatives, in the Capitol, sup- 
ported as it is by twenty or thirty pillars formed of the solid rock, and 
l^laced in an amphitheatrical range; each pillar about three feet in 
diameter, and twenty in height. Some idea of the labor which is em- 
ployed in working the marble may be formed from the fact, tliat the 
expense of each pillar is estimated at five thousand dollars. The speci- 
mens in your possession, are good examples of its general structure, 
but convey no adequate idea of its beauty." 

The words of commendation and the beauty of the columns of the 
Capitol led the regents of the Smithsonian Institution to investigate 
the locality and to consider the availability of this rock for the build- 
ing of the Smithsonian Institution. Accordingly in the spring of 
1847 Dr. David Dale Owen visited these quarries which, on the whole, 
he found were worthless for the pixi-pose in hand. 

At the present time the work in the Potomac marbles is earned on 
almost exclusively by the AVashington Junction Stone Co., which 
quai-ries both sandstone and Potnmac marble. The former is obtained 
in good sized blocks but the latter is wrought almost entirely in small 
slabs. The marble is taken from a small opening about half a mile 
southwest of the quarry buildings. The conglomerates under discus- 
sion belong in the Xewark fcmnation, which extends along the western 
border of the Piedmont Plateau from Connecticut and JSTew York 
southward. The development of the Potomac marble within the 
Newark is not great and there are Init few exposures within the state. 
It is sparingly developed north of Frederick, a mile south of Thur- 
mont and only barely represented at Point of Rocks on the eastern 
slopes of the Catoctin Momitain. According to Mr. Keith' this lime- 
stone conglomerate occurs in lenses or wedges in the sandstone ranging 
from 1 foot to 500 feet in thickness, or possil)ly even greater. They 
disappear through complete replacement by sandstone at the same 
horizon. The wedge may tliin out to a feather edge or may be bodily 

' Keith, Geology of the Catoctin Belt, 14th Ann. Kept. U. S. Geol. Snrv., 
\V:ishington, 1894, p,art ii, p. 34(). 



MARYLAND GEOLOGICAL !>l]iVF.Y 11)1 

replaced upon its strike by sandstone; one method is perhaps as eoni- 
iTion as the other. 

The conglomerate is made up of pebbh's of limestone of varving 
size whieh sometimes reach a foot in diameter, although usually aver- 
aging- aboTit two or three inches. The fragments, which are both 
well rounded and angular, range in color from gray to blue and dark 
bhie, and occasionally 7)ebblcs of quartz, ehloritic schists and white 
crystalline niai'ble occur. All are embedded in a red calcareous matrix 
mixed with a greater or less amount of sand. The pebbles are very 
similar to the magncsian limestones of the Shenandoah formation, 
developed in the Frederick and llagerstown valleys and to the rocks 
of the com])lex which forms the Catoctin Mountain. Occasionally 
])ebbles show evidences of having been decayed even before they 
became a j)art of the conglomeritic nuuss, but this may be due to their 
greater solubility, since the uiatrix does not show a corresponding de- 
gree of decomposition. 

The bedding so far as it has been observed is irregular and of little 
importance in the quarrying of the rock, the lenticular character of 
the beds having far more importance than the position of the indi- 
vidual pebbles within the mass. In the same way the jointing is also 
a relatively subordinate feature since the different degrees of cohesion 
between the i)arts of the pebbles and that between the pebbles and 
the matrix i>lay an important part in deternuning along what planes 
a rupture will take place. The texture shows a wide variation in the 
size of the grains, in the chai'acter of the material composing them, 
and in the relative amount of matrix between the grains and pebbles. 
This wide range in the size of the particles and in their abundance 
leads to many difticidties in polishing the rocks, but the difference 
between the hardness of the limestone and that of the quartz pebbles 
is particularly a source of expense and annoyance, since the hard quartz 
pebbles break away from the softer parts in which they lie, leaving 
numerous cavities to be filled with colored wax or shellac. This differ- 
ence in the hardness and nuiterial of the pebbles, together with the 
conglomeritic character of the mass excludes the use of hammers and 
chisels. Any satisfactory quarrying of the blocks must b(> done with 



192 A HISTOEY OF THE QUARRYING INDUSTRY 

saw and abrasive materials. It is this difBculty in the working, to- 
gether with the fragile nature of the stone itself, which has kept it 
from the conspicuous place in the market, which its oddity and beauty 
deserve. 

The chemical composition of breccia can scarcely be determined 
from a single analysis, and the figures obtained from an average of 
several analyses may be of little account. The values obtained de- 
pend A-cry largely on the accuracy of the analyst, the fineness of the 
grain, the homogeneity of the specimens and the number of samples 
taken to make an average test. Higgins ' gives the following as " the 
average of various analyses made of the Breccia marble, or Calico 
limestone, found in Montgomery, from which the pillars in the House 
of Representatives at Washington are made: " 

Sand 12.3.5 per cent. 

Iron and clay 1.00 

Lime, as carbonate 70. .50 

Magnesia 1.5.00 

Otlier constituents not wortliy of estimation 0.2.5 

Total ilil.OO 

This is probably of little value in itself and should have no weight 
in estimating the value of the marble. The stone is particularly 
suited to mosaic work and interior decorations, and should not attempt 
any competition as a structural material with the stones now in com- 
mon use. 

The influence of microscopic structures in a stone like this breccia 
is more than over-balanced by the variations in the larger structural 
features of the rock. If the microscope or hand lens shows that the 
stone is sufficiently fine and homogeneous to take a good polish with 
few minute irregularities on the surface that is sufficient, still experi- 
ence clearly shows that this rock will take a good polish and that it 
will withstand any pressure to which it may be subjected as an orna- 
mental or decoi-ative stone. 

This unique material deserves to be fully exploited and pushed as 
a novelty in the highest class of interior furnishings. It is believed 
that a demand might be created for this stone in some of the best 

' Second Kept. Ju.s. Higgins, State Agr. Cliemist, Annapolis, 1852, p. .39. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II. PLATE XXIV. 




Fir.. I.-WIIITEFURI) QUARRY, GAXIHKI.A. IIAIU'OHU ilOUXTY. 




l-'Ui. -J.-SLATK ijr.VUliV. I.I.\MS\ li.LK. i'iiKUKUli.K (.ul.MV. 



JLAKVI.A.ND GEOLOGICAL SURVEY 193 

work which is done in New York, Philadelphia, Washington and other 
large cities, where tliere is a call for materials which are suitable fi)r 
floors and other interior decorations, striking in color and texture and 
of pleasing contrasts. 

SERPENTINE. 

Serpentine or " Verde Antitjiie " has been (pi.initd in Maryland 
for many years, but the annnal production has always remained small. 
As this rock enters into competition with some of the marble for in- 
terior decoration it has frequently been classed as a marble, although 
so far as the Maryland deposits are concerned it is in no wise related 
to the marble, however intimately interwoven with calcite veins it 
may be. The deposits of the state are found in Cecil, Harford, Balti- 
more, Howard and Montgomery counties, where they have been 
worked to a greater or less extent in the hope of obtaining good ma- 
terial for general building or interior decoration. The most thor- 
oughly exploited are those about Baltimore, at the Bare Hills, those 
on the banks of Broad Creek in the eastern part of Harford county, 
and a small area near Cambria in the northern part of the same 
county. That the stone is capable of furnishing beautifid slabs for 
decorative purposes is readily seen from the accompanying illustration 
(Plate XXV). The deposits on Broad Creek are situated in the midst 
of a large serpentine area, which extends from the Susquehanna south- 
westerly into Baltimore county. The nearest town is the small vil- 
lage of Dublin some three miles to the south, which is lacking in 
both railroad and canal c<imnuinication. In the shipjting of orders 
it is necessary to have all of the stone hauled to Conowingo on the 
Perryville and Columbia Bailrond, a distance of three or four miles. 

It is not known when the quarries on Broad Creek were first opened. 
Local tradition asserts that they were operated some years before the 
civil war. It at least seems probable that they were opened as early 
as 1870, since at the time Professor Genth made his report (1875), 
some of the shafts had been worked to a depth of 57 feet. The area 
was still earlier the scene of mining operations for iron, and it prob- 
ably was prospected for chrome deposits about the beginning of the 
century. In 1875 the Havre Iron Co. of Wilmington, Delaware, 
asked Professor P. A. Genth of the University of Pennsylvania to 

13 



194 A HISTORY OF THE QUAEKYING INDUSTRY' 

visit the area for the purpose of " examining into the nature and ex- 
tent of the deposit of Green Ornamental Stone " occurring on their 
property. The results of this visit were published in a small pamphlet 
entitled " The Geological Report of the Maryland Verde Antique 
Marble."' How long this company operated for serpentine could not 
be ascertained, but evidently the quarries were not worked in the 
period just prior to ISSO, when the Serpentine ^larble Vo. liegan oper- 
ations in this district. This company operated the quarries in a more 
business-like way, constructing sawing sheds and polishing tables as 
well as a short railroad across Broad Creek on which they removed 
the refuse. The quarries when visited by the writer were not in opera- 
tion on account of the lack of success, extravagant management and 
litigation arising from the death of the mortgagee, «'li(i held a mort- 
gage on the property for $40,000. During the activity of this latter 
conqiany considerable material was furnished for building purposes 
and for interior decoration, tlie principal market lieiug Xew York, 
where the material was used entirely for decoration. The largest 
building constructed of this material is the Protestant Episcopal Grace 
Memorial Church of Darlington, ild. 

The geological occurrence and the mineralogical character are simi- 
lar to those of the serpentine deposits all along the eastern border of 
the continent, which occur as alteration products of basic niagnesian 
rocks like peridotite. The clianges which have taken place show all 
of the features of serpentinization with the development of accessory 
deposits of calcite, quartz, opal, gibbsite, deweylite, etc. The rock 
face of the quarries rises quite sharply from the bed of Broad Creek 
and offers every facility for operating above water level, and for the 
handling of the stone at little expense. There does not appear to be 
any marked bedding in the rock, although Genth seems to have re- 
garded the mass as possil)ly of sedimentary origin. The ledge which 
has been worked seems to form a lens of more massive rock lietween 
more micaceous and schistose layers, the long direction of the layer.-^ 
having a strike of N. <i!)° E. Tbo seaming of the rock is its least 

' The Geological Report of the Maryland Verde Antique Marble and other 
Minerals on the lands of the Havre Iron Co. in Harford County, Marjland, 
by Prof. F. A. Genth, University of Pennsylvania, 1873, 9 pp., map. 



MAEYLA.ND GEOLOGTCAL SUUA-KY ll*.") 

favorable feature, since the seams niii irrt'a\il;iily lioth in direction ami 
ami ill distance, causing the stone to break up into irregular masses, 
whicJi require considerable handling before they can be reduced to 
good form. The rock also gives evidence of having undergone cou- 
si(]cr:il>l(' (listiirliiiiice, as shown Viy the liands of fibrous serpentine 
wliicli arc often faulted to tlic distance of i or f of an inch (Plate 
XXV). This seaming and faulting cause considerable \va.<te and 
render the stone tender, so that it must be shipped with care and used 
where it is imt subject to great pressure. 

The texttire of the stone does not vary very widely, and the im- 
pression is left that the stone works readily. If due care is used to 
avoid the use of explosives and the working of the stone after it has 
lost the s(i-calh'd qiiarrv water much of the waste may be avoided. 
The use of diamond drills or channelling machines offers tlie only 
method which will jiistify the expectation of profitable work. The 
stone as described by Genth ' "is a variety of massive serpentine, 
somewhat r('seml>ling wiliiamsite, and shows sometimes a slightly slaty 
structure. Tt occurs in various shades of green, from a pale leek- 
green to a deep blackish-green, and from a small admixture of mag- 
netic iron, more or less clouded; vavdy with thin veins of dolomite 
passing througli the mass. Tt is translucent to semi-transparent; it is 
exceedingly tough, and its hardness is considerably greater than that 
of marble, scratching the latter with great ease." 

'I'lie analyses of the deep green translucent and lihick mottled varie- 
ties gave tlie fallowing results: 

Silieio acid 40.06 4il.::!i 

Alumina 1.37 l.lll 

Chromic oxide 0.20 trace. 

Niccolous oxide 0.71 0.3:! 

Ferrous " 3.43 0.!)7 

Mauiranous ■• O.Oil trace. 

Magnesia 39.02 38.32 

Water 12.10 12.86 

.Magnetic iron .3.02 fi.22 

100.00 100.00 

Hardness 4.00 4.00 

Specilic gravity 2.068 2.660 

' I.oc. fit. ]). 7. 



196 A HISTORY OF THE QUAERYING INDUSTRY 

Merrill states in his " Stones for Building and Decoration " that 
the " spociiic gravity is 2.6G8, which denotes a weight of IfifiiJ- pounds 
per cubic foot, or practically the same as granite. Specimens of this 
stone received at the National Miiseum admitted of a very high liis- 
trons polish, the colors being qnite nniformly green, slightly mottled 
with lighter and darker shades. It is not a true verde antique in the 
sense in which this name was originally employed. So far as can be 
judged from appearances, this is a most excellent stone, and admirably 
suited for interior decorative work." 

Since the rock has Ijeen formed under conditions not far different 
from those existing at the surface, it is probable that no considerable 
degree of chemical decomposition will take place; the source of danger, 
however, lies in the tendency toward physical disintegration, brought 
about by pressure and frost action. The beauty of the rock, when 
polished, fits it pre-eminently for service as an ornamental stone, and, 
when used in the interior for ornamental veneering, the rock is not 
subjected either to harsh atmospheric action or to any detrimental 
amount of pressure. 

What has been said of the Broad Creek quarries may equally well 
be said of the smaller opening operated by W. Scott Whiteford about 
three quarters of a mile southwest of Cambria, a small station on the 
Baltimore and Lehigh Railroad not far from Cardiff. This is the 
only quarry which has made any shipments during the last year. The 
opening whence the material is obtained is now filled with water and 
does not appear at first sight very favorable. As represented in iho 
accompanying figure (Plate XXIV, Fig. 1), it is still small and 
there is considerable opportunity for expansion. The transportation 
facilities are good and the supply of material is sufficient to permit 
successful competition with other serpentine areas. 

The rock worked seems more suitable than in many of the aban- 
doned openings of serpentine, since it is fii'uicr and somewhat more 
schistose. If the sawing is done parallel to the schistosity the expense 
is less and the slabs are relatively stronger. Cutting in this direction 
does not give quite as pleasing a texture to the surface, liut the 
general effect is good. The stone from the Whiteford quarry is 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXV. 




srriM':ntink. 

IIROAI) t REKK, H^KIORO <OlNr> . 



MARVLAXD OEOLOOICAL SUUVEY 107 

lighter aiul iimre mottled tlmn that IVdiii BniaJ Crceh. In its mot- 
tling it rc.-^cnibles i\w \n-odnct from abandoncil openings near White 
Hall, Baltimore county. 

The plant includes maehinei'v for sawing, grinding and polishing 
the rock by steam power and the operators have shown that in spite 
of the difhcnlties to be overcome lieantiful slabs of polished stock 8' x 
4' X 2" may be obtained. 

LI.MES-I'OXES. 

The blue and gray limestones of Paleozoic age have never been 
(juarried in ^Maryland as building stones except for local use. The 
most important and in fact the only one which has been used in promi- 
nent buildings is that from the Shenandoah formation of the Hagers- 
town and Frederick valleys. According to the Report of the 10th 
Census this rock is a magnesian limestone containing alumina and 
graphite, while earlier analyses made by Dr. James Higgins ' show a 
wide range in the composition of specimens from different portions 
of the Plagerstown valley. 

Analyses of /Jniestonc. 



SiO, 


5. 80 


0.:.'.5 


2.40 


3.00 


0.70 


2.00 


0.60 


0.00 


0.20 


2.00 


Al,()3 1 
Fe,0, i 


0. 10 




0.«0 


0.27 




0.04 


0.00 


.20 


0.10 


0.30 


CaO* 


50. TO 


.■>G. 18 


.5;i07 


B0.2] 


oO. 70 


ol.frt 


.'•).'>. 18 


.i0.7'.l 


.54.32 


53.20 


Mj;0* 


1..-.7 


l.:U 


LOT 


20. 3T 


21.12 


14.(10 


0.41 


1.43 


1.1(1 


1.24 


CO.j 


41..=iS 


-14.01 


42. ST 


46.00 


47.40 


41.113 


43.81 


41.48 


43.00 


43.16 


Undt. 


0.13 


.25 


tr. 


tr. 


tr. 


0.00 


0.00 


0.00 


0.30 


0.10 



* Computed from CaCO, and .MgCO,. 

The quarries, according to Prof. Chas. E. Monroe, are on a belt 
locally called Cedar stone, a few hundred feet in width extending for 
a distance of several miles, and believed to be peculiar in the fact 
that the upper layers furnish the most desirable stone. 

This stone is of a deep blue color when freshly quarried, but u[)<>n 
exposure there is slowly formed a thin white coating over the face of 
the rock, which brightens the color to a dove-gray, thereby greatly 
improving the appearance of the buildings. This change goes on uni- 
formly and accordingly does not pass through the unsightly mottled 
stage. 

' 3r(l Report, p. 135. 



198 A ni.STOliV OF THE quareyixg ixdustky 

There is no doubt that this rock might become of considerable im- 
portance economically as a building stone. At present, however, the 
residual soil, with which it is covered, lends itself so readily to brick 
making tliat there is little demand for stone except in heavy structures 
or for foundations. 

Many other areas in the Hagerstown valley offer limestones which 
may ultimately prove of importance as building stones. Openings in 
the rock are made only for lime at the present time, and the methods 
of quarrying, which sliatter the rock by heavy charges, make the 
exposvu'es look less favorable for the production of building stone than 
is actually the case. If proper care in extraction were exercised, there 
is no doubt but that large blocks of limestone could be quarried in 
many places throughout the entire valley, which would in some in- 
stances work into a good grade of " black marble." 

In the Frederick valley little has ever been done towards quarry- 
ing the blue limestone for building purposes, as almost all of the stone 
which has been taken oiit has been burned for lime which finds a ready 
market. The buildings in Frederick show that there has l^een some 
quarrying for building material, since se\'eral of them are built of 
limestone and almost all of them have limestone foundations or sills. 

"West of the Hagerstown valley in Washington, Allegany and Gar- 
rett counties there are three Paleozoic limestones, namely the Lewis- 
town, Rockwood and Greenbrier. Of these the first is the only one 
which oft'ers reasonable grounds for expecting good building material 
within its limits. The upper massive beds of the Lewistown which 
outcrop in five or six small bodies along the Potomac from Hancock 
to Cumberland, and form a continuous belt from the latter point to 
Keyser, West Virginia, afford every indication that satisfactory build- 
ing material may be obtained. Little if any work has been done in 
this formation because there have been no local demands.' 

Of the two remaining formations the Rockwood is of such a nature 
that it cannot be iised at all, and the Greenbrier is scarcely any better 
adapted to building purposes. Both formations occur in \-alleys with 

" It is a matter of interest in tliis connection to note that outside of Cum- 
berland and Frostburg there is scarcely a stone building in either Alle- 
aany or Garrett counties. 



MARYLAND GEOLOGICAL SURVEY 



VOLUMF II Dl «TF X«VI. 




< to 




I 



ilAKYLAMJ llEULOlilCAL SURVEY IDD 

very few outcrops. The latter division has a single exposure on the 
Potomac between Keyser and Piedmont, West Virginia, and is im- 
perfectly shown on Jennings Hun and Bradchu-k's linn. It is also 
iiijiin'd fur sti-m-lural |iiir|)nscs liy the pyvite which (ic('Ui"s scattered 

tluMlHgh it. 

S.VNDSTONES. 

Although there is but one sandstone within the state which has 
attained any considerable rc])utation as a building stone, there are 
many formations in different parts of the area which furnish suitable 
sandstones for local construction. As is the case with all building 
stones the factor of transportation facilities is so im[)ortant that only 
those deposits can come into general use which are situated adja- 
cent to prominent lines of travel either by railroad m- boat. The 
sandstones of the state range in geological age from those which are 
sup])osed to 1)0 Archean to those which l)elong to the Triassic period. 
According to their age and im])ortance they may be considered 
under the following heads: tiie Triassic sandstones, the Paleozoic 
sandstones of the Pocono, Monterey and Tuscarora formations, the 
Camhrian or Mountain sandsfoncs, and the Micaceous sandstones of 
the eastern Piedmont area. Their distribution is shown cm Plate 
XXX. 

THE TRIASSIC SANDSTONES. 

The Triassic or " Seneca Red " sandstones are the only ones quar- 
ried in Maryland which possess a recognized reputation in the market, 
or which furnish materials for more than local work. The formation 
in which they occur is extensively developed along the eastern edge of 
the United States from Connecticut southward through iN'ew York, 
N'ew Jersey, Pennsylvania, and Virginia, and in scattered areas into 
Xorth and South Carolina. It is from rocks of the same age that 
the well-known building stones from Portland, Connecticut; Pralls- 
ville, Xew Jerecy, and Hummelstown, Pennsylvania, are qnarried. 
This formation enters Maryland from the north near Emmitsburg, 
and continues with varying width through Carroll, Frederick and 
]\rontg()mery counties to the Potomac river. Between these limits 
there is an almost edUtinudHs licit l<ically known as the " red lands," 



200 A HISTOEY OF THE QUAEEYING INDUSTRY 

which is divided into two areas by a small exposure of the underlying 
Shenandoah limestone a few miles west of Frederick, where the whole 
of the Triassie has been removed by stream erosion. 

In either direction from this point the formation widens to about 
16 miles at the Mason and Dixon line and 4 miles where it crosses 
the Potomac. East of this belt in the southwestern corner of Mont- 
gomery county there is also a broad area of the same formation which 
is continued southward into Virginia. It is to this southern area 
that the quari-ying of sandstone is almost entirely confined. The 
prominent quarries are situated near the mouth of Seneca Creek, 
Jfontgomery county, on the Chesapeake and Ohio Canal about 23-25 
miles northwest of Washington. 

Seneca Creel-. 

The first use of this stone is not known, although it is evident that 
blocks of this material were utilized in the construction of the old 
Potomac canal built around the Great Falls of the Potomac in the 
year 17Y4. From that time until the present these quarries have 
been worked more or less systematically to supply the demands for 
local buildings and for shipment. During the extension of the Chesa- 
peake and Ohio Canal from 1827 to 1833 considerable material was 
quarried for the construction of aqueducts and embankments, which 
is still in a state of good preservation. About this time, or soon after, 
some of the quarries of this area came into the possession of Mr. John 
P. C. Peter of Montevideo, near Darneystown, ^lontgomery coimty, 
Maryland, who was the owner of the quarries at the time when the 
stone was obtained for the Smithsonian Institution in 1847. Before 
the rock for the above building was quarried the area about Seneca 
Creek was visited and the quarries then opened were carefully exam- 
ined by Dr. David D. Owen.' Somewhat later, after the stone had 
been adopted and the quarries practically selected, James Rcnwick, 
Jr.," architect for the Institution, visited the quarries with a view of 
ascertaining their capability of affording a sufficient quantity of build- 

' Keport of Board of Regents Smithsonian Institution, Jan. 6, 1848, Sen. 
Doc. notli Cong-ress, 1st Session, No. 33, pp. 36-39. 
- Same pp. 105-107. 



ArAKYI.AM) GEOLOGICAL SIRVEY 201 

iiii;- materinl of nnifoi-nily pidd quality and cdldr. From tlic reports 
iif tliesc jientlcinon wc learn that at that date there were several quar- 
ries which had been opened and worked usually on a royalty of 25 
cents per pereh for all stone quarried. 

The (juarry most extensively operated at that time was the so-called 
■' College quarry," which lay about a quarter of a mile farther west 
than the quarries owned by Mr. Peter on Bull Run, from which the 
stone for the Smithsonian was obtained. Messrs. Peter, L(>e and 
Vincent seem to have been the most prominent opei'ators in the 
aica. Ill 1807 Mr. Peter sold his quarry to Mr. II. TT. Dodge, 
\v]\n ciroanized the oriiiinal Potomac Med Sandstone ('(Jinpany, a com- 
pany wliich ui'carly dcvclopt'd the quarries and marketed a large 
amunnt of the stone, principally in Washington. In 1874 the com- 
pany became involved in litigation, and the quarries were closed for 
nine years. In 1883, the company was reorganized, and the work 
pushed rapidly forward until June, 1889, when the canal, iipon which 
the company depended for transportation, was washed out and the 
quarries lay idle for a period of two years. In 1891 Mr. George 
Mann, of Baltimore, purchased the property and foiuided the present 
organization, " The Seneca Stone ( 'ompany,'' which has worked the 
quarries during the last seven years. 

The beds from which the building stones are now obtained lie west 
of Seneca Creek, on the left bank of the Potomac river, where the dip 
is some 1.5 to 20 degrees to the southwest. This inclination of the 
lieds allows the quarrying to be carried on from the south and south- 
west without very much stripping and little or no binding from over- 
lying strata. The openings show that the available material is dis- 
tributed in workable bods, varying in thickness from eighteen inches 
to six or seven feet. These are separated from each other by bands 
of inferior material of different color and texture. The sandstone beds 
themselves differ very mvich, not only in color but also in hardness 
and texture. Some are fine-grained and can be wrought to a sharp 
arris; others are coarse-grained and may assume the character of a 
conglomerate. Interstratificd with these grits are argillaceous shaly 
beds, wliich, together with some of the conglomeritic beds, are entirely 



202 A IIISTOKV OF THE QUAKRYING INDUSTRY 

initit for the lietter grades of work, and cannot compete with local 
sti)ni' for rongli foundation work on account of the cost of transporta- 
tion. In strata showing as wide variation as these do it is natural 
that only a portion i)f the material excavated is available, and there 
must necessarily be a considerable waste. Occasional clay holes in 
the lower grades, which produce unsightly holes on exposure, increase 
the \vaste, but these do not affect the character of the better grade of 
stone, since they may be avoided by a careful selection of the ma- 
terial. The bedding of the rock determines the direction and manner 
of operating the quarry, while the presence of two series of joints 
greatly facilitates the extraction of the material. These joints run 
normal and parallel to the strike of the bedding. The first stands 
perpendicular to the dip and the second is practically vertical, so that 
the blocks obtained are more or less rectangular. The distance be- 
tween the joints varies from a few inches to se\'eral feet, liut average 
satisfactorily for economical quarrying. 

The texture of the stone which is placed upon the market is ex- 
ceptionally good. It is very fine-grained and uniform and is not at 
all shaly, and shows little or no disposition to scale when exposed to 
the weather. The particles of quartz are e\'idently distributed through 
a fine, scarcely perceptible cement, and over the entire face there are 
very minute flakes of muscovite which brighten the general appear- 
ance of the rock. Occasionally in larger lilocks there are seen small 
bands of coarser grain which indicate the bedding, and in a few in- 
stances this alternation in texture is emphasized by variations in the 
color of the cement. 

One of the most valuable features of the Seneca sandstone is the 
extreme readiness with which the stone may be carved and chiseled 
when it is first quarried. It is then soft enough to be easily cut and 
the textTire is suificiently uniform to render the stone satisfactory for 
delicate carving. As is frequently the case with all building stones 
the rock after exposure loses the readiness with which it may be 
worked and becomes hard enough to turn the edge of well tempered 
tools. It is this hardening on exposure which protects and preserves 
the delicate tracery sometimes seen in the finer examples of dressing 
in l)locks from these quarries. 



I 



.\rARVi.AM) (iKoi.OGKAi. sujtVEV 2();5 

Tlic cdlnr (if tlic Seneca Creek sandstone as furnished l>y the Stnieca 
Stone ( 'iiiii|i;niv varies from a liomnpeneous lig'lit reddisli lirown or 
einnamdii In a cdiocolatc or dvv\) [lurpU^brown. When freshly ([uar- 
ricil tlie colors arc c\cii hrighter than after the rock has been ex- 
posed sonH> time, the rock presenting tones of a light reddish fawn 
color. The color changes with the composition. With an increase 
in quartz the histre of the rock becomes brighter and with an increase 
in feldspar the tone of the rock becomes grayer, while an increase in 
the amount ot cement deejiens the color. 

The rock under discussion when studied microscopically is found 
to be composed of angular grains of quartz, micro<'linc, plagioclase 
and muscovite. The first three of these minerals occur in more or less 
clearly detined polygons, which al)Ut each other without interlocking. 
They show no uniform direction in the position of their longer axes. 
The same is true of the muscovite which occurs in long narrow shreds. 
This lack of interlocking lietween the grains causes large interstitial 
spaces which render the rock friable, porous and absorbent tuiless they 
arc tilled with some cement. In the Seneca stone the spaces are 
almost entirely occupied by a natural ferruginous cement which in- 
creases the strength of the rock. The relations between color, cement 
and porosity are indicated in the first two determinations by Page, 
given Ix'low. The individual grains are covereil with films of iron 
oxide and there seems to be no evidence of enlargements due to the 
secondary deposition of silica. The plagioclase grains show some alter- 
ation, but those of the luicrocline are usually fresh and unclouded by 
decomposition products. Since the plagioclase is present in very sub- 
ordinate amounts its alteration does not materially decrease the 
strength of the rock. 

A cin-sory examination of some of the old litiildiugs made of stone 
fr(nn Seneca Creek leaves the iui|ir(ssion that at least part of the rock 
from this loc-ality is unsuitalile for fine buildings liecause of its low 
crushing strength and its tendency to scale. This apparent defect in 
the rock arises from two causes, the lack of care in the selection of 
material, and in the cutting of the blocks so that they will rest par- 
allel to their beddinc when set in the buildinas. Material where such 



iJ04 A HISTORY OF THE QITARKYING INDUSTRY 

scaling appears does not represent the better grade of Seneca stone but 
is coarser, showing more evidences of cross-bedding, and it is also much 
richer in mica and poorer in cement. There seems to have been a 
constant tendency among the earlier builders and stone cutters to 
place the rock, not on "' bed," but on " edge." Many of the promi- 
nent structures which now give evidences of flaldng or spalliug 
clearly show all of the defective blocks to be on " edge." In all rock 
like the poorer grades of sandstone, such a position speedily brings 
out the inherent weakness of the rock. The only determinations of 
crushing strength available, prior to the present study, were made 
many years ago by Dr. Chas. G. Page and published by Walter R. 
Johnson ' in the American Journal of Science. These give the aver- 
age crushing weigiit per square inch as 2691 pounds. This value was 
obtained on two separate specimens, one of which was from the Smith- 
sonian Institution. The fact that both rocks give the same values 
indicates a marked uniformity in the strength of the better grades of 
rock. The tests recently made show the strength per inch as high as 
18,625 pounds per square inch (see below). 

The weight and disintegrating effects of frost upon the Seneca 
sandstone Avere carefully studied by the Brard method before the 
stone was accepted for the Smithsonian Institution, and we have as 
a result of Dr. Page's " investigation the following determinations: 

Specific Lost l)y frofet 

gravity. in grains. 

D.ark red Seueca saudstoue (similar to Peter's) 2.672 0.70 

Liglit Seueca sandstone, dove-colored 2.486 1.78 

Dark coarse sandstone, of Seneca aqueduct, Peter's 

quarry not ascertained. 5.60 

Sandstone four miles above No. 3 D, Peter's ue.xt 

vpest Beaver Dam quarry not ascertained. L.'iS 

Dark sandstone, from quarry near Woods' resi- 
dence not ascertained. o. ',14 

The specific gravity of these rocks indicates that the weight per 
cubic foot of the stone is l.j-t to 165 pounds. These figures seem to 

' Comparison of Experiments on American and Foreign Building- Stones 
to Determine their Relative Streng-th and Durability. Amer. .lour. Sci., 2 
ser., vol. .xi, 1851, p. 7. 

-Report of the Board of Regents Smithsonian Institntion, Senate Doc., 
.30th Congress, 1st Session, No. 23, pp. 21-22. 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXVIII. 




Vic. l.-SA\DSTO.\K IJlAlMtY. KM M ITSIill'.r.. FltKllKlUGK GOUN'TY. 




^53^'. 









Fig. -'.-SA.XU.STUXI:; ULAUKY. SKXKGA. .MU.XTUU.MKHY COUXTY. 



MARYLAND GEOLOCilCAL SURVEY 205 

indicate that the Seneca rock is slightly heavier than the usual run 
of brownstones, which, according- to the table given by Hopkins/ 
range from 127.5 to 100. 1, with an average of 161.4 pounds. In 
structures the Maryland and Pennsylvania stones will range between 
apjiro.ximately the same limits. 

The various tests recently conducted bv the Survey are very favor- 
able to the Seneca rock. The specimens examined were in two-inch 
eul)es cut from stock furnished to one of the stone yards of Baltimore. 
The figiires below thiis represent the average run of the quarry and 
not especially selected stock. 



Simple crushing. 


Absorption. 


Freezing. 


Crushing after 


freezing. 


Craclc. 


Breaii. 




2,368 


0.000 


73,700 


74,. 500 


72,380 












2, .530 


0.013 


0.5, S40 


R!),500 


(i'.i.onn 


.... 








(i7,.5(i0 











0.5,240 

The mineralogical and chemical composition leave nothing lack- 
ing as to the promise of permanency in the Seneca sandstone imder the 
action of atmospheric agents. There are no deleterious minerals in 
rlie carefully selected stone which may injure its wearing power, and 
the chemical analyses show that the constituents arc in stable combi- 
nations. The microscopical exauiinations also show (Fig. 14, p. 97) 
iliat the cement firmly binds the interlocking gi-ains without lea^^ng 
any considerable interstitial spaces in which moisture may lodge to 
destroy the integrity of the rock. This lack of porosity is shown 
also in the slight loss by freezing, as given in the above tables. 

The best e\'idence of durability is foiind in the structures which 
have been made of this material. Owen reports (1847) that " Ijy 
close inspection of slabs exposed now 20 years to atmospheric agencies 
and severe mechanical friction, the mark of the dressing-chisel is still 
sharply imprinted in the surface. On the perpendicular wall of the 
aqueduct, where the water has been oozing through the joints and 
trickling down its face, forming an incrustation of carbonate of lime, 

' The Building Materials of Pennsylvania, No. 1 IBrownstone. Appendix 
to the Ann. Rept. of renii. State College, Official Doctimeiit Xo. 22 for 1S90, 

pp. :;o-3i. 



20G A HISTORY OF THE QUAEE.YIXG INDUSTRY 

one may observe, wliere this calcareous cnist lias scaled off, the 
grooves and ridges of the surface still nearly as distinct as when the 
block first came from the hand of the stonecutter. 

'' The angles and edges of the keystcnics of tlic arch, placed under 
these must unfavorable circumstances, are sharp and entire. Only 
one or two lilocks of this work of 20 years' standing show sign of 
decay; but these seem to lie such as either have not been well selected, 
or have been placed on the edge in the wall. 

" Even the tow-path of this aqueduct, over which the horses pull 
and mules have been traveling 20 years, is still unimpaired. Even 
the corners around which the heavy lock-gates swing, show no signs 
of chipping." 

^Merrill later (1891) corroborates these observations and says: '' On 
blocks of the stone in the aqueduct of the Chesapeake and Ohio Canal 
which have been constantly permeated by water every season for fifty 
years, the tool-marks are still fresh and no signs of sealing are visible 
other than are produced by too close contact at the joints. . . . The 
Smithsonian Institution erected in 1S48 to 1S.54 from this stone, 
shows few defects from weathering alone, and these only in those 
cases where they might have been avoided by judicious selection." 

Xo discoloration has been noticed in the rock beyond the darken- 
ing which gradually and uniformly takes place on exposui'e. 

Minor Areas. 

Throughout the entire extent of the Triassic as exposed in Mary- 
land there are small local quarries developed to supply the demands 
for foundations and occasionally for more pretentious building. The 
general demand, however, is more than overcome by the cost of trans- 
portation in all but the most favorably situated localities. There are 
many occurrences which will prove of value as the country becomes 
developed and improves its facilities for distributing its resources. 
Among the most promising of these smaller openings is one located 
near Taneytown and owned by John Yingling. This quarry is sit- 
uated on the western side of a little hill on the road leading from 
the Emmitsbui'g pike to Harney, not far fnmi the former. The rock 
exposed is more feldspathic than any iif the Triassic sandstones now 



MAKYI.AM) GEOLOGICAL SURVEY 207 

worked in the state. It is bright gray and gives a pleasing impres- 
sion, which is in accord with the present demands for light and cheer- 
ful trimmings. The stone has been tested and the crushing streiigtii 
and absorption for two-inch cnlics is as below. 

I. II. Absorption. 

Crack (iT/.tOO jjoiincls. il4,0{l(> pounds. 0.004 

Break !I4,000 •■ 109,400 

The rock is, therefore, strong and when niMnipulalcd ])r(iiK'vly may 
be extracted in blocks of snfheient size to meet ordinary demands. 
The means of drainage and the (>])])ortnnitv for dumping waste are 
favorable, wliilc the distance from the (piarrv ti) the railroad is not 
far enough to render competition iinsuccessfid. The smaller quarries 
which have been worked spasmodically include the cpiarries just north 
iif Emmit.sburg, and several ojR'nings about Taneytown, Thtirmonf 
and Union Mills. 

It is not improbable that suitable rock might be found in tin- 
vicinity of Bruceville, where the railroad facilities are esjiecially 
favoral)le. 

"Washington Junction. — The oidy other source of red aii<l brown 
sandstone from the Triassic formation of ^laryland, which enters into 
competition with the Seneca stone, is ii(>ar AVashington Junction in 
Frederick county. Here the AVashington Junction fStone Company, 
capitalized at $30,000, carries on considerable work in extracting and 
dressing the red, brown and variegated sandstones. The present 
operators began work in 1892, and have continued quarrying almost 
continuously ever since, furnishing much stom! for such Imildings as 
the l'"ort McHenry Hospital, Baltimore, churches at Forest Glen, 
Maryland, and Winchester, A^irginia, and many houses in the l)ettcr 
part of AVashington. 

The beds from which this sandstone is obtained di]) gently to the 
west, and thus afford opportunity for the economical extraction of 
the stone. Blocks 20 x 6 x 4 feet may be obtained if the demand and 
the machinery warrant. The stone does not differ noticeably from 
that furnished at Seneca but shows the same pleasing color and tex- 
ture already noticed in the latter jilace. The (piarries are well eqni])- 
ped with saws, rubi)ing beds, polishing machines, etc. The chief 



208 A HISTORY OF THE yUAEBYIXG INDUSTKY 

drawback in the location of tliis opening, which is a mile and a half 
from the railway station, is removed by a small spur track which ex- 
tends from the quarry to the station and to the wharf on the Chesa- 
peake and Ohio Canal. 

The general mode of working the quarry is shown in the accom- 
panying figure (Plate XXIX, Fig. 2), which inadequately represents 
the ledge whence the material is obtained. 

PALEOZOIC SANDSTONE. 

Among the various later Paleozoic formations there are four which 
develop well marked sandstone series. These are the Pottsville, the 
Pocono, the Monterey and the Tuscarora. Xone of these have been 
worked to any considerable c-xtent as liuilding stones, because of the 
lack of demand and transportation facilities. 

The Pottsville Formation. — The Pottsville is the lowest division 
of the coal measiires and forms the mountain ridges which border the 
coal basins. It consists of sandstone and conglomerates interstrati- 
fied with sandy shales in which thin beds of coal are locally developed. 
The sandstones are usually coarse-grained and conglomeritic, with 
marked evidences of cross-bedding which are irregular in extent and 
disti'ibution. The individual pebbles, frequently very small, are held 
together by a siliceous cement, which indicates great durability for the 
rock. ITnfortiuiately such a cement renders the working of the stone 
l)oth difficult and expensive. It is probable that this material will 
never become of economic importance except in the supply of local 
demands for foundations, steps and occasional door sills. 

The Pocono Formation. — The Pocono formation is very similar 
to the Potts\'ille and consists mainly of hard, thin-bedded flaggy sand- 
stones which occasionally become sufficiently conglomeritic tn produce 
confusion between the two formations. The sandstones of the former 
have received but little attention and have been used only occasion- 
ally as a supply for flagging. It seems quite probable that as the 
demand for building stones increases the flags, which are well devel- 
oped in places, may come to be of some importance. 

The Monterey and Tuscarora Formations. — These two forma- 
tions have a considerable development in Allegany and Washington 



MARYLAND GEOLOGICAL SURVEY. 



VOLUME II, PLATE XXIX. 




HitrmiPrf^, 



Fv:. l.-MOXOCACY AUTKlIt CT. WliriK (JT AHT/lTl': I'ltuM liKI.T'S (ilAJiHY. 




I'l.;. V.-SA\liMii\K ijl \|;i;Y. I'nl\r i IF imrKS. I'HKUERlClv COLWXV. 



MAKYL.VXD GEOLOGICAL SCKVEY 209 

counties, where the stone lias been used to supply the local demands. 
This is especially true of the area about Cumberland. Here the Mon- 
terey sandstone, which is of a buff-brown to yellow color, was the first 
to be introduced. It is the source of all of the sills, foundations and 
lintels for the older buildings. The most important structure in which 
it is exclusively employed is the Episcopal church. Time has shown 
that the very property for which the stone was first chosen, viz., the 
ease Avith which it is cut, is detrimental and that it, together with the 
clay holes which seem to be developed frequently, leads to the ready 
disintegration of the rock, so that many of the steps, sills and 
foundations of the older buildings are in quite a dilapidated state. 
Where this stone was used in curbing the blocks have become rounded, 
or broken or deeply worn. The stone itself when dressed presents 
a very pleasing appearance, especially in trimmings, where it coin 
cides with the present tastes in architectural work. It is quite pos- 
sible that by careful selection good material might be obtained from 
one of the several quarries in Cumberland to supply the .demands foi' 
a light gray or yellow trimming stone. As a clew in the choice of 
material it may be stated that as the number of fossils decreases the 
rock becomes harder. 

Although the Monterey has not proved altogether satisfactory about 
Cumberland there are other points in the distribution of this forma- 
tion where it seems probable that good material may be obtained. The 
best of these is the quarry owned by Mr. B. S. Randolph of Frost- 
burg, which is located in Washington county near Dam jSTo. 6 of the 
Chesapeake and Ohio Canal. The opening, which was made for glass 
sand and not for building stone, is in the form of a timnel from 
thirty to forty feet deep, and is situated about SOO yards back from 
the canal and from 400 to 500 feet above it. The stone is of clear 
creamy-white color and would make a bright trimming or structural 
material. At first sight the rock looks as though it is too friable and 
not strong enough to endure pressure, but the experiments show that 
in two-inch cubes it has a crushing strength of 73,780 poimds on 
edge and 75,600 normal. This indicates that the first impressions 
are incorrect and that the rock is capable of withstanding any ordi- 

14 



210 A HISTORY OF THE QUARRYING INDUSTRY 

nary pressure. The purity of tlie rock is attested by the following 
analyses made by O. ( 'reath of Pottsville, Pa. : 

1. 2. 3. 4. 

SiO,, 99.255 99.5.58 99.398 97.55 

AljOs 610 .341 .47.3 3.44 

CaO 110 0.81 .103-1 .01 

MgO tr. tr. tr. j 

FeO .037 tr. 

FeO 025 0.20 

100.000 100.000 100.000 100.00 

When it was found that the Monterey sandstones were not as 
durable as expected and that they soon became disfio-ured by exposure, 
attention was directed to the harder white sandstones of the Tusca- 
rora which are exposed in Wills Mountain just west of Cumberland. 
The ledge here exposed has a thickness of some 300 feet, but the solid 
rock has not yet been quarried, since the demand is more readily sup- 
plied by utilizing the many detached blocks which cover the slopes 
of the mountain. At the present time this stone is used for foun- 
dations and trimmings in all of the better class of buildings in Cum- 
berland, and its character is well shown in the Presbyterian church. 
The rock varies somewhat in texture and firmness according to the 
different beds, but on the whole shows unusual uniformity. It is 
bright gray in color and is composed entirely of fragments of quartz, 
which are themselves cemented by a siliceous cement, causing the 
rock to be in reality a quartzite rather than a sandstone. Feldspar 
and mica are also found in the rock. Few imperfections were noticed 
and for one of such siliceous character the rock seems to be very free 
working. 

The chemical composition, as might be inferred from the mineral 
contents, is largely silica. Professor C. F. Chandler ' in his report 
on the mineral resources of Cumberland gives the following analysis: 

Silica 98.35 

Sesquioxide of iron 0.43 

98.77 
' See Tenth Census, vol. x. Report on Building- Stones, p. 178. 



MARYLAND GEOLOGICAL SURVEY 211 

while a more complete one furnished by the present operators is as 
follows: 

Silica 98.00 

AI3O3 65 

Fe,03 15 

CaO 40 

MgO .21 

Alkali tr. 

Water and organic 50 

!)9.!)1 

'i'li(' Tuscarora sandstone unlike that of the Monterey shows great 
dnraliility in whatever position it may he placed, and it is accordingly 
nsed in almost all of the local work on the embankments of the Chesa- 
peake and Ohio Canal and in foundations wherever there is a con- 
siderable superstructure. It is also used to great advantage for pav- 
ing, curb-stones, steps and trimmings. 

Besides the prominent sandstone formations of the Paleozoic al- 
ready mentioned and that of the Cambrian considered below, there 
are scattered throughout the series numerous small beds of sandstone 
which arc sometimes utilized to supply local requirements. The quar- 
ries which have l)een opened are scarcely worthy of the name and the 
product from all of them is insignificant. 

Cambrian ok Moixtaix Sandstone. — There extend across the 
state two parall(>l bauds of dense quartzites which form the Blue Ridge 
and Catoctin mountains. These quartzites were originally porous 
sandstones, which have subsequently been thoroughly consolidated by 
a dense siliceous cement. Similar rocks also occur in the small de- 
tached area of Cambrian .sandstones which forms Sugar Loaf Moun- 
tain. The rock has never been brought prominently into the market, 
altliough it lias been used quite extensively for railroads, canals, roads 
and a few individual buildings. It is not known when the first work 
was done here, but according to Schai-f the quarries at Sugar Loaf 
were operated quite extensively prior to 1830 to furnish stone for the 
old canal. At this time there was a traniroad several miles long ex- 
tending from the quames to the canal. The rails were .stnplings 
and the tram cars were hauled by horses. This little railroad ante- 
dated the Baltimore and Ohio and has practically disappeared, road 



212 A HISTORY OF THE QUAEEVING INDUSTRY 

bed and all. During the succeeding decade the Sugar Loaf stone was 
used in the Baltimore and Ohio Railroad, which has continued its 
use occasionally ever since. 

Other quarries have been opened in a small way along the Western 
Maryland Railroad to supply the demands for good road metal and 
small quarries have been operated l;iy the Mount St. Mary's authorities 
at Emmitsburg. The latter furnish a stone of dense, even texture in 
which there can be little absorption and little consequent loss by the 
action of frost. The crushing tests show that its strength is ex- 
ceptionally great as a two-inch cube sustained a weight of 93,900 
pounds before cracking and 104,200 pounds before breaking. In 
buildings the rock appears of a bright fresh gray color which darkens 
but little on exposure. Its general appearance is well shown in the 
recent additions to the Imildings at Mount St. Mary's. The siliceous 
character of the rock renders it difficult to work in other than the 
natural face, but its durability, strength and compactness render it 
unsurpassed where great permanence is desired. 

There are within the area of Cambrian sandstone above enumerated 
many exposures of rock which deserve more careful investigation and 
which no doubt would prove of service if the transportation facilities 
were at hand. At present the demand is not enough to warrant any 
workings beyond the occasional operations carried on at the McGill 
Belt Quarry at the base of Sugar Loaf Mountain and the incidental 
quarrying at Mount St. Mary's, near Emmitsburg. 

MICACEOUS SANDSTONES OF EASTERN MARYLAND. 

Scattered over the northeastern portion of ^Maryland in Baltimore 
and Harford coimties are several exposures of highly micaceous quartz- 
ose rocks, which were originally sandstones, but which have now 
imdergone considerable change through dynamic metamorphism. 
These are most characteristically developed in Setter's Ridge along the 
Green Spring Valley, ten miles north of Baltimore, and on the Balti- 
more and Lehigh Railroad near Pylesville, and eight or ten miles 
south of the Mason and Dixon line where the railroad crosses Deer 
Creek. 



MARYLAND GEOLOGICAL SURVEY. 




MARYLAND GEOLOGICAL SURVEY 

WM Q. CLARK STATE QEOLOQIST 

1898 
LEGEND 

TUSCARORA S. S. | tV \ POTTSVILLE CONG (_ 



CAMBRIAN S. S 



POCONO S. S. 



: 



QUARTZ SCHIST | 9 | ORISKANY S. S. 
TBIASSIO S. S. I N i SLATE 



VOLUME !!. PLATE XXX. 




urn BV A MOen A CO. BAITO. 



.MARYLAND GEOLOGICAL SURVEY 213 

Beer Creek Sandsiones. 

At the station known as " The Rocks," the Baltimore and Lehigh 
Railroad and the Deer Creek pass throngh a ridge of highly metamor- 
phosed hard mioaceons sandstones in a gorge 350 feet below the sum- 
mit. This ridge extends in a northeasterly and southwesterly direc- 
tion for a distance of ten to twelve miles and forms a part of the 
folded phyllite series wliich arc probal)ly of Cambrian age. The sand- 
stone of wliich it is cnuijiosed lies geologically some distance above the 
base of the series and below the bottom of the Peach Bottom slates. 

The stone is a micaceous sandstone rich in quai-tz wliich locally 
becomes clearly conglomeritic. It contains more or less white mica, 
rjddritc and bluish kyanite which are the product of secondary crystal- 
lization due to the metamorphism. The schistosity is well marked 
and in many instances minute flutings and crinklings are noticeable, 
producing in a cross section of the rock a somewhat pleasing figure 
and lustre. This stone has long been used in the surrounding country 
for foundations, sills, steps, and hearthstones, and its fire-proof char- 
acter was early appreciated by Dr. Thomas Johnson of the U. S. 
Army. In 1891 a company known as the " Maryland Cranite' Com- 
pany " was organized to develop the material as a building stone. 
T'ables were strung to deliver the stone on board the cars and con- 
siderable work was accomplished in preparing for quarrying. The 
company soon ceased operations, either beca\ise satisfactoiy rates were 
not made with the railroads or because there was no demand for the 
stone, which was n<it a granite cither in cliaracter, origin or even in 
appearance. 

In the northern extension of this ridge, about Pvlesville, the rock 
becomes less congiomei'itic and micaceous. It has never Ijeen worked 
for any purpose in this vicinity, but if the demand should arise it is 
highly probable that the area will offer suitable material for a me- 
dium grade building stoue. 

Setter's Ridge Quartzite. 

Setter's Ridge is a prominent topographical feature along the south 
bank of the Green Spring and Mine Bank valleys from Green Spring 

Junction on the Xortheni Central Ivaih-ond to Suuinierfield on the 



214 A HISTORY OF THE QUARRYING INDUSTRY 

Baltimore and Lehigh Railroad. It is composed of a thin series of 
highly micaceous beds of quartz-schist which are sharply separated 
from the overlying limestones on the north and merge more or less 
gradually into the gneisses on the south. " Whatever the origin of 
the quartz-schist may have been it is closely allied to the gneiss into 
which it grades. ... It is not improbable that this peculiar rock 
represents a fades of the gneiss produced by some dynamic agency, for 
it always shows the effects of intense mechanical action and motion." 
This fonmation never attains any considerable thickness and it always 
occurs as a series of beds of quartzite of varying thickness, separated 
by parallel layers of muscovite, in which are emplanted numerous 
shattered tourmaline crystals which appear stretched and drawn out 
in the manner described and figured by Williams.' The readiness 
with which the quartz-schist cleaves into broad slabs well fits it for 
flagging. It is quarried at a number of points in the Green Spring 
valley, but it is most extensively worked at the Shoemaker quarries 
al)Out one-half mile west of Stevenson Station. From here it is trans- 
ported for considerable distances and may often be seen in founda- 
tions and bridge abutments. It is a rock of low quality, and quarried 
in a careless way and at present is of little economic importance. 

Slate. 

general distriiiution. 

When Tyson made his first reconnaissance of the state as Agri- 
cultural Chemist in 1859 few industries appealed to him more strongly 
or seemed to promise greater returns' than the quanying of slate. 
That his view, which was based on the fire-proof quality of slate 
roofs alone and did not take into account their durability or pleasing . 
appearance, has not been fully realized, is due to factors beyond his 
control. Other states have gained the advantage by superior mer- 
cantile energy. At the time of his ^'isit three quarries were in opera- 
tion in Harford county, while smaller openings had been made for 
slate at Hyattstown, Ijamsville and Linganore. None of the latter 
are now in active operation, but the Ijamsville area will be treated 
briefly after a discussion of the Peach Bottom region. 

' Guide to Baltimore, p. ]04. 



MARYLAND GEOLOGICAL SURVEY 215 

THE FEACH BOTTOM AREA. 

The slate produced in the quarries of the Peach Jiottom district 
of Maryland and Pennsylvania is the most widely known structural 
material manufactured within the limits of the state. I'nfortunately 
Maryland has received little credit for its share in the industry al- 
though almost all of the productive quarries are situated \vithin its 
limits. This apparent injustice has arisen from the fact that the 
shipping point for most of the quarries and the residence of many 
of the operators is Delta, Pennsylvania, a town lying at the foot of 
the ridge which supplies the stock for the manufacture of slate. Delta 
is so much better known than its Maryland associate, Cardiff, that 
mail is received through the Delta postoffice by inhabitants li^ang 
scarcely one himdred yards from the Cardiff office. 

The topographic relations between the town and the quarries are 
particularly favorable for the shipment of slates and the establishment 
of a prosperous commimjty. The town is connected with the princi- 
pal cities of the Atlantic seaboard by the York and Peach Bottom 
Eailroad (broad gauge) which forms a portion of the Pennsylvania 
system, and the Baltimore and Lehigh Railroad (narrow gauge) which 
runs from Cardiff to Baltimore. The latter railroad, because of its 
small cars and narrow gauge, permits shipment of slates no farther 
than Baltimore, where trans-shipping to broad gauge cars is necessary. 
When it is broadened, as is now contemplated, the shipments from 
Cardiff will no doubt increase and Maryland will receive a more just 
jiroportion of the credit for the manufacture of one of the most per- 
fect slates produced in the world. 

The quarrying of slate in the Peach Bottom area is divided chro- 
nologically, according to the nationalities of the quarrymen and the 
methods of quarrying, into two well defined epochs, the first ending 
■with the arrival of the Welsh immigrants during the years 1845 to 
]860. During the first period the workers were not professional 
quarrymen, skilled in the manufacture of slate. The Welsh, on the 
other hand, were trained in the art from their childhood, and many of 
them are known to have been employed in the Festiniog quarries of 
northern Wales. There is no information at hand from which we mav 



216 A HISTORY OF THE QUAEKYING INDDSTEY 

learn when the presence of valuable roofing slates was first recognized 
in this area or when the first material was taken out for roofing pur- 
poses. According to the local tradition, which is subject to some 
doubt, the slates were quarried as early as 1750. The building on 
which these slates were laid was destroyed a few years ago and the 
inferences concerning its age are based on a series of deeds and family 
papers which seem to indicate the date of construction as 1749 or 1750 
and the source of the material as some point on the ridge not far to 
the north of the Mason and Dixon line. The first authentic evidence 
of quarrying is the slate recently removed from the roof of the old 
Slate Ridge Church, known to have been built in 1S05, which was 
torn down in 1893. The slates from this old roof which had been 
exposed to the atmospheric agents of degeneration for eighty-eight 
years show no change in color or firmness, although some of them 
were covered Ijy lichens and other vegetable growths. The slabs of 
slate used ranged in size from large pieces three feet sqiiare in the 
lower courses, to small ones three by seven or eight inches near the 
ridge pole. Some of the larger slabs have been preserved by the 
quarry superintendent to show the great stability of their stone, even 
when poorly prepared and poorly laid. These pieces are irregularly 
cut and more or less imevenly split. The stock used is not equal to 
the first or even the second quality of slates furnished at present. 
Prior to the coming of the "Welshmen Avith their improved methods 
of working, the limit of the quarrying was the " Big Red " clay ' 
which is the limit of weathering and the point to which the ledges are 
now stripped. When the hard rock was reached in earlier times, work 
ceased, since explosives were not used to cut a " head " or to loosen 
the rock. The earlier workers also had no adequate methods of trim- 
ming their slates and tradition says that their splitting chisels were 
mattocks. 

During this period of early work the most prominent operators were 
Messrs. Carmen and Docker, two Englishmen who obtained a lease of 
the land, including the quarry now operated by R. L. Jones, a short 
distance north of the state line. These gentlemen, with Peter Wil- 
liamson as foreman, opened and operated a quarry from 1812 to 1817, 

'Shown at the point of stripping reached by the men in Plate XXXI, Fig. 1. 



MARYLAND GEOLOGICAL SUHVEV. 



VOLUME II, PLATE XXXI. 



■ \ 


'^^^B^''^^^^V^I 


\ 

4 




- 
i 





itl'- 



"•^t? 



"^ o 

3 c 

•Jj o 

O «; 

X s 




'/. a 

— o 



- o 



ArAEYLAND GEOLOGICAL SURVEY 217 

when it was abandoned hecanse competition with the Welsh prodnet 
was unremunorative. The Welsli slate at this time was shipped to 
America as ballast and admitted free of duty. 

Aboiit the same time (1812) Mr. Sinclair made an abortive attempt 
to produce slates successfully on the " A. B. Miles property." The 
location of his opening was between two quarries whicli have sulise- 
quently been worked with greater or less profit. Nothing is known ol 
this operator beyond the facts enumerated, except that he seems to 
have left the country about 1817 at the time when Carmen gave up 
his work. During the seventeen years from 1S17 to 1834 no work 
was done along that portion of the Peach Bottom district which lies 
west of the Susquehanna. Mr. Williamson, however, seems to have 
removed to Lancaster county and to have carried on the manufacture 
of slates in a small way during the interval. The property whence 
he obtained his material belonged to a Jeremiah Brown. 

In the fall of 1834 Carmen returned to Delta and wished to sell 
his lease as the quarry had been so unremunerative that he had 
changed his business. His former foreman, Mr. Peter Williamson, 
finally bought the lease and began operations which have continued 
in this locality up to the present. The rental paid by ^Ir. Carmen to 
Mr. McCandless for the entire tract was $36 a year and the priee paid 
by Mr. Williamson for the land in fee simple was $12,000. Slate at 
this time, whether from Welsh or American quan-ies, sold at about 
$20 a ton, or approximately $5 a square, as slate is now figured. The 
first lease to Welsh immigrants was granted by Williamson about 
1845, when two families by the name of Davis (an uncle and nephew) 
began operations after the improved methods with which they were 
familiar in the old country. The Davises took a lease of a portion of 
the ridge just north of the Mason and Dixon line and worked a quarry 
for two years, when the same was leased to Roland Perry, a recent 
arrival from Wales. Mr. Perry gi-eatly developed the industry, and 
soon had in his employ a force of sixty to seventy-five men, who turned 
out a highly improved grade of slate. About the same time Johu 
Humphrey, another prominent operator of the area, with otheiv 
worked a quarry near West Bangor and became very successful. Both 
Perry and Humphrey cleared about $50,000 or $60,000 each, during 



218 A HISTOEY OF THE QUAEKYING INDUSTRY' 

tlieii" operations. Their method of working the quarries seems, how- 
ever, to have been somewhat faulty as they were inclined to follow 
down a " vein " without sufficient breadth, until at a depth of 160 to 
176 feet the loosened and insufHeiently supported top rock either 
caved in or rendered tlie working of the quarries exceedingly dan- 
gerous. 

The first quarry south of the state line operated by the Welsh meth- 
ods was opened by Mr. Kobert Griffith some time in 1847 at the loca- 
tion of the present York and Peach Bottom quarries. This was the 
only firm working south of the llason and Dixon line during the suc- 
ceeding decade. The power until 1855 was supplied by horse wind- 
lass, when a steam engine was added to the equipment in urder to 
pump the water from the pit. Griffith successfully operated the 
quan-y for several years. At his death the work was continued by 
Samuel M. and Hugh C. Whiteford, his administrators, who made 
and sold a large amount of slate. The quarry leased was then sold 
to Isaac Parker of New York for $18,000. This property, together 
with that operated by Proctor Bros., and all the slate lands extending 
and bounding on the Mason and Dixon line on the east, belonged to 
Tlionias Hawkins, who entci-ed it previous to 1776. 

Thomas Proctor came to this countiy about the same time with 
Carmen, Docker and Sinclair. As general managers, Sinclair and 
Proctor opened a quan-y on the Hawlrins property, on the north side 
of the i-oad 200 or 300 yards northeast of the now York and Peach 
Bottom quarry. In the meantime Tliomas Proctor married Eliza- 
beth, only daughter of Thomas Hawkins, and became possessed of 
part of Thomas Hawkins' estate and built on it, amongst other struc- 
tures, a stone spi'iiighouse, which is still standing covered with slate 
from this quan-y. This, according to one tradition, was the first slate 
roof put on, and antedates that of Slate Ridge church which was 
taken from the same quai-ry in 1805. This quarry was operated by 
a few hands in 1812, as the father of Mr. Wm. G. Coulston brought 
from them a flag for a dooi-step, dressed about 5 feet long, 2i feet 
wide and 3 inches thick. The hands put it down for him and it 
remains the same to-dav. 'Jlie vein was narrow and did udt work to 



MAKYI.AXD GEOI-OGTCAI, SUKVKV 219 

profit and was aliaiKluiiiMl. j\Ir. Proctor tried otlier j)laces witliout 
success, and it was left to his gi-andsons to profit by his ovcrsiglit. 

Duriiii;- tii(^ year ls.")S IJichard Griffith, of i'liiladclphia, ih» coii- 
nection of tlie above named Robert Griffith, opened a quarrv iii the 
lower portion of the nortlnvest side of the ridge, not far from the 
present town of Cambria. This prospecting opening was sold to a 
syndicate composed of Samuel Bottime (President), W. P. Polton 
(Superintendent and Local Manager), and otliei's, who attempted to 
operate the quarry. The whole project was abandoned the following 
year. The failure was due to the selection of a jjlace of opening on 
the very edge of the slate formation instead of at some point on the 
top of the ridge nearer the center, where tlie stock is much better. 
This syndicate at that time held land which carried the best beds of 
slate known at present, since some ten years later, April 8, 1SG8, the 
present " Peach Bottom Slate Company of Harford county, .Mary- 
land," rented their site from tiiis company on a thirty year lease. The 
Peach Bottom Slate Company worked on the lease for a few yeai-s 
when at the death of one of the owners, according to the laws of the 
state then in force, the entire property was offered for sale. Follow- 
ing the advice of Col. Webster of Bel Air, who was interested in the 
company, the lessees bought that portion of the estate which they had 
held by lease and in 1878 were incorporated as a company with tlie 
above title.' 

' The history of this proiierty, which contains the most active quarries, 
is quite involved. After the property which Kichard Griffith bought of tlio 
Whiteford estate proved worthless, the 25 acres adjoining, which includes 
the Peach Bottom, Peerless, and Excelsior quarries, were sold by Jlichael 
Whiteford to .lohn Morrison for $500. (His eldest son says that his fatlier 
Michael received no money, but took it out in shoemaking and mending 
for his family and bond servants). Mon-ison willed the land to his 
daughter, who married Thomas Wright. Mrs. Wright oifering the land 
by an agent, Joseph D. Wilej-, found no bidders, and svibsequently be- 
queathed it to her five daughters, one of whom sold her lots to a com- 
pany composed of John Humphrey, Kichard Kees, Owen Owens, Ben- 
jamin Williams and Jones. One other daughter sold her portion 

to a company— Thomas W. Jones, John Parry, William Thoma.s and Wil- 
liam Parry. This lot was sold by the minor heir: in consequence the pur- 
chasers afterward had trouble in perfecting their title. The price of each 
of these lots or portions was $1200. 



220 A HISTORY OF THE QUAKEYIKG INDUSTRY 

In the fall of 1870 John Pan-v, William AY. Thomas, Thomas W. 
•Jones, William Parry, Catherine Jones, and others formed the Welsh 
Slate Company which leased four acres adjacent to that of the Peach 
Bottom and opened the " Ilickoi-y Hill Qnany," subsequently work- 
ed by the Peerless Slate Company of Pittsburg for a terra of ten years 
ending in July, 1898. 

In 1873 or 1874 the Welsh Slate Company throngh ]Mr. Parry 
bought the land for $12,000 and other considerations, a figure which 
shows a marked increase in the vahiation of the pi'opei'ty since 1850, 
when 25 acres, inclnding all of the quarries now operated was offered 
for sale for $1,200 and found no takers. Since the pmperty liought 
hv 'Sly. Parry was deeded by a minor there developed a great lawsuit 
concerning the oAvnership of the property and it was only after con- 
siderable expense that the company cleared its title to the land. 

The Excelsior Quarry was first operated by a small company, who 
bought a little land in 1860 and operated until the spring of 1861, 
when the work was stopped by the enlistment of most of the owners, 
who themselves worked in the quarries. This land was sold to Isaac 
Parker after the war and later come into the possession of William E. 
Williams & Co., who leased it to two parties soon after on short leases. 
The quarries have been operated under leases ever since the land be- 
came the possession of the present owners. The cjuarries operated 
at present by Proctor Brothers, who started work in 1893, was first 
operated about 1868 but was not worked very much until under the 
present regime. 

In 1880 Persifor Erazer' in his repoi-t on the Peach Bottom slates 
in York County and Maryland says that the following quarries suc- 
ceeded each other beginning at the state line and proceeding south- 
ward into Maryland at the time they were visited in 1877: 

Kilgore & Co.'s, James Perry it Co. (has been idle several years); 
Wm. E. Williams & Co. (leased and operated by the York & Peach 
Bottom Co.); Wm. C. Koberts (owned and operated by Proctor Bros.); 
John Humphrey & Co. (Peach Bottom Slate Co.); Thos. W. Jones 
& Co. (idle for several years, now o-wned by Peerless Slate Co. who 

' Geology of Lancaster county, Second Geological Survey of Pennsylvania, 
CCC., Harrisburg, ISSO, pp. 182-lflO. 



JIAKVLAND GEOLOGICAL SURVEY 



221 



have laade a new opening recent l_v); John W. Jones &■ Co. (S miles 
south of state line along the ridge) ; Hugh E. Hughes & Co. (idle about 
ten years). 

The accompanying sketch shows the location of the al)andoned and 
active quarries within the State of Maryland at the time of their study 
for tlie present report in 1^9G. 




Fig. 19. — Sketch map of Peach Bottom Slate area. 



Shtc Quarries at Delta, Pa. 



Faulk Jones <fc Son, (w) 11. 

(a) 12. 

(w) 13. 

U. n. .Joues it Co., Tunnel, (w) 14. 

E. W. Evans & Co., (w) ].i. 

R. L. Jones, (a) KJ. 

CM IT. 

State line. 18. 

Slate Springs, (a) I'.t. 

Delta & Peach Bottom. (w) 20. 

Schwab's Quarry, (a) 21. 

(a) Abandoned, 



Scarborough's Quarry, (a) 

Baltimore & Peach Bottom,(a) 
Henry's Quarry, (a) 

York ifc Peach Bottom, (w) 
Proctor Bros., (w) 

Peaeh Bottom, (w) 

Excelsior, (w) 

Peerless, (w) 

Aiken & Co.'s. (w) 

Stubbs or Cambria, (w) 

Baltimore A I'l'acli Hottum. (a| 

(wj WOrklns;. 



The geological ]>osition of the beds, which furnish the slates of 
the Peach Bottom district, is in either the Hudson River or Quebec 



222 A HISTORY OF THE QUARRYING INDUSTRY' 

series, probably the latter as determined by Professor James Hall in 
1883 from fossils submitted to him by Dr. Persifor Frazer.' 

The productive beds are thought to lie the axis of a narrow over- 
turned synclinal fold which is included within the phyllite forma- 
tion, extending in a northeast-southwest direction across eastern Mary- 
land. The stratigraphic position of the band is still in some doubt, 
since no detailed mapping of the area has ever been completed. Just 
below the slates, which form the top of the well-defined topographic 
features called the " Slate Ridge," is a band of talcose chlorite slate 
which runs parallel to the roofing slates on either side of the ridge. 
These talcose slates are in turn underlain by a metamorphosed quartz 
conglomerate which resembles that of the exposures at the Rocks of 
Deer Creek. This quartzitic conglomerate wraps about the end of 
the slate formation some fifty feet below the exposure of the slate. 
To the southward the bands of conglomerate from either side coalesce 
and form a continuation of the slate ridge, which extends outhwest- 
erly across the Broad Creek at Pylesville, where Broad Creek has 
cut a well-defined gorge. While few, if any, observations have been 
made upon the true bedding of the slates and while no satsifactory 
contacts have been found in recent studies in the area, the workings 
along the ridge seem to point conclusively to the fact that this syncline 
is somewhat overturned to the east, so that the dip of the westerly 
side is practically coincident with the cleavage, as is claimed by the 
quarrymen. The slate ])elt itself forms a narrow zone beginning a 
short distance southwest of the road running from Cambria to Pros- 
pect and extends in a northerly direction more or less parallel to the 
" Slate Ridge " through Maryland and York county, Pennsylvania, 
to the Susquehanna river, which it crosses. There is a short exten- 
sion of the formation east of the Susquehanna in Lancaster county, 
which at times has lieen the most productive portion of the belt. 

Throughout all of that j^art of the area Avhich has furnished good 
slates the bedding is not clearly defined and the ledges of first-class 
material do not seem to present any continuous arrangement, suggest- 
ing valuable beds separated by non-productive ones. This lack of 
definition in the bedding of the stone renders it impossible to com- 

' Tran.s. Amer. Inst. Miii. Eng., vol. xii. 1SS4, p. 3.JS. 



-MAUVI.AM) (GEOLOGICAL SURVEY 223 

piite with any degree of .iceuvacy the thickness of beds or '' veins." 
Some of the quarries produce good slate over a distance of a least 150 
feet across the strike and their operations are limited not by the quality 
I if tlic stone but by a short-sightedness during early operations which 
allowed the rubbish to be dumped upon the workable beds. 

All of the quarries along the line show a great many series of joints 
which both aid and hinder the working of the quarries. The principal 
or bedding joints, as observed in the Proctor Brothers' opening (shown 
in Plate XXXI, Fig. 1) strike cross the cleavage and dip at an angle of 
42° to the southwest. Similar bedding joints were observed in the 
I'each Bottom and York and Peach Bottom quarries (Plate XXXlPj. 
In addition to this most clearly marked jointing, there is a second 
series of joints dipping at an angle of 26° with the same strike 
and another set of joints which dip at abo\it 80° to the northeast with 
their strike normal to the cleavage. These three systems free the 
rock in large rhomboidal slabs and they, if they existed alone, would 
be very valuable aids in quarrying the rock. Unfortunately besides 
these somewhat uniformly inclined joints there are a great many 
other jointing planes developed through the beds which do not seem 
to- be conformable to any system of arrangement. They cut each 
other at all angles and intersect the plane of cleavage either acutely 
or with considerable obtuseness. In the York and Peach Bottom 
quarries there are sharply defined uneven jointing planes which leave 
the rock protruding like a series of folds whose axes lie parallel and 
separate from each other at a distance of one to three feet. The ma- 
terial on each side of the curved jointing planes (see Plate XXX 11, 
Fig. 1) is of the same character and there is no evidence to warrant rlic 
assumption that there has been a direct bending into small folds either 
prior or subsequent to the development of the cleavage and the other 
jointing planes. The great number of joints and their intersection 
with each other at varying angles renders much of the material ex- 
tracted \inavailable for the manufacture of roofing slates or mill stock. 
While this is so and the amount of rubbish about the quarries is very 
great it is doubtful if there has been a greater portion of waste ma- 
terial than is common in slate quarries the world over. Another fac- 



22-4 A HISTORY OF THE QUAEEYING INDUSTRY 

tor wliicli must be regarded by practical o[)eratijrs working in the 
Peach Bottom area, is the presence of " flint seams " and " blue 
joints " which modify the manner of working the stone and fre- 
quently render much of the material worthless. The " flint seams " 
are of at least two classes; those of the first occur in long thin layers 
along the jointing planes where the two sides of the joint have been 
separated sufliciently to allow the deposition of quartz. The second 
class includes much more irregular deposits which occur in irregular 
masses varying from a fraction of an inch to several feet in diameter. 
These apparently represent zones of more intense crushing and subse- 
qvient deposition of quartz since it is a common saying among the 
quaiTvmen that the seams cleanse the rock and make the cleavage 
finer and truer. The " blue joints " referred to are really closed joint- 
ing planes in which chlorite has been deposited in more or less com- 
plete orientation with the chlorite of the body of the slates. The 
seams are not evident at first, but during the splitting and trimming 
of the slates develop as lines of weakness which render the pieces ob- 
tained of no value. 

The most prominent feature in the texture of the Peach Bottom 
slates is the coarse fibrous arrangement of the particles which give 
to the stone an appearance somewhat suggestive of the fibre of petri- 
fied wood. This texture renders the slates much stronger in certain 
directions than they might otherwise be, but precludes the method of 
breaking the slates by sharp blows applied normal to the cleavage 
and makes the stock unavailable for luilling purposes. The peculiar 
" fibrous " texture of the slate is indistinctly shown in Plate XXXI, 
Fig. 1, which represents the combined opening of the Peerless, Peach 
Bottom and Excelsior quarries. This also renders the use of the 
" plugging machines " and similar instruments of doubtful value. It 
has also been found more economical and feasible to saw the slates 
across their grain. The material prepared for market shows little or 
no variation in the nature of the stone employed, but the character of 
the finished product seems to vary somewhat in different quarries. 
Xot only is there a difl'erence in the skill with which the work is done, 
but the quarrymen seem to differ in the amount of care which they 



HAKYLAXD GEOLOGICAL SURVEY 225 

exercise in sorting the first and second qualities. Wliilc different beds 
and different portions of the quarry furnish stock that differs in the 
ease with which it is worked and in the character of the finished pro- 
duct, the qiiarrymen say that good material may he obtained from all 
portions of the opening and at all depths below the zone of superficial 
weathering. In company with qiiarrymen from all regions the men 
hold to the Ix'lief that the rock improves indefinitely with the depth. 

The color of the Peach Bottom slates is a deep blue-black which is 
absolutely unfading, as is shown by the color of slates which have 
been exposed since the beginning of the century. This fact alone 
places the product of the area among the best slates of the world. 
From this color there seems to be no variation in any of the well pre- 
pared material. It should be borne in mind, however, that slates, 
like broadcloths, when placed side by side with their texture in differ- 
ent positions show differences in their sheen and that these differences 
may l>ecome so marked that an impression of a variation in color is 
often given. Care must be exercised accordingly not only in the 
selection but also in the laying of the slates if the most desirable effect 
is to be obtained. The imfading quality of the Peach Bottom slates 
allies them ^\^th the products of the Maine and certain of the Ver- 
mont quarries and sepai-ates them from the less unifoi-mly colored 
slates of the Lehigh and Slatington districts which are not always 
able to retain their color unmodified by exposure. The only influ- 
ence of exposure in the Peach Bottom slates which has been noticed, 
is a slight increase in the gloss or sheen in those pieces which have 
been longest exposed to the sun and atmosphere. 

The bulk composition of any building stone may be very misleading, 
since it does not show in what state the chemical constituents are com- 
bined. This is especially true with slates. It, however, is of consider- 
able advantage in showing the lack of injurious elements and the 
presence of advantageous components. The valuable constituents in 
the slates are the silicates of iron and alumina, while the injurious 
constituents are sulphur and the carbonates of lime and magnesia. 
Three analyses of the Peach Bottom slates are given below, one by the 
Pennsylvania Geological Survey made in 1 877,' one by Booth, Garrett 

' Second Keport Laboratory of the Survey, bj- .\ndrevv S. JlcCreath, Har- 
risburg-, 1879, p. 370. 
15 



226 A HISTOEY OF THE QUARRYING INDUSTRY 

and Blair of Philadelphia in 1885, and one by George P. Merrill.' 
They are as follows: 

Analyses i>f Slates. 

Pa. Geol. Sur. B. G. & B. Meriill. 

SiO, 5.5.880 .58.370 44.15 

TiO,, 1.370 tr. tr. 

AljOg 31.849 31.985 30.84 

^«=0 \ 9 034 10.661 14.87 
Fe,03 J 

MnO 0..586 tr. tr. 

CaO 0.155 0..300 0.48 

MgO 1.495 1.303 0.27 

CoO tr. 

K^O \ 4 ;^oo 1.933 4.36 

Na,Oj 

H.,0 3.385 4.030 J 0.51 

CO,^ 0.390 (. 4.49 

C ' 1.974 0.930) 

S 0.107 wanting. 

SO, 0.33 

FeS, 0.051 

99,801 99.909 99.97 

These analyses show the percentage of deleterious and advantageous 
minerals as follows: 

Geol. Surv. B. G. & B. Merrill. 

Silicates of iron and alumina 86.763 91.016 89.86 

Sulphur 0.039 0.107 wanting. 

Carbonates of lime and magnesia 3.319 3.066 1.435 

The source of the material for the first analysis was the " J. Hum- 
phrey (fc Co.'s quarry," now the Peach Bottom, and the second 
was also from the same opening. The material for the third analysis 
was taken from the opening of the Peerless quarry about one hundred 
feet west of the limits of the pit of the Peach Bottom. In describing 
the source of the materials Merrill gives the following description of 
the mode of weathering of the slates: " In the fresh cuts made dur- 
ing the work of stripping, to open new quarries, the sound rock is 
overlain by a variable thickness of ferruginous residual clay. Joint 
blocks and splinters of the slate scattered through this clay, in all 
stages of decomposition leave no doubt as to its origin. Blocks, deep 
velvety black on the interior, are surrounded by a crust of ocherous 

» Rock, Kock Weathering- and Soils, 1897, p. 229. 



MARYLAND GEOLOGICAL SURVEY 



VOLUME II, PLATE XXXII 




FiG. i.-YoUK .\.\]l I'KAGilliuT'ruM UL:A1:UY, CAMBltlA. 




I'lu. -J. XuXlii A\U rKACllHUTTOM QUARRY. CAMBRIA. 



MAKYLA.ND GEOLOGICAL SURVEY 227 

brown-red decomposition product, the decay penetrating irregidarly 
like the processes of oxidation into a piece of metal. The first physical 
indication of decay is shown by a softening of the slate, so that it 
may be readily scratched by the thumb nail, and an assumption of a 
soapy or gi'easy feeling, the entire mass finally passing over to the 
deep red-brown unctuous clay, sufficiently rich in iron to serve as a 
low-grade ochre, for paints. .The incidental chemical changes are sur- 
prisingly large, as shown by the analysis below, column T 1 icing an 
average of two analyses of one of the blocks, and II that of the resi- 
dual clav. In III. IV, and V are siven the calculated losses of con- 



^tituents." 














i. 


n. 


1)1. 


IV. 


V. 


Conetitncnijj. 


Fresh Aritllllln. 


Kesidiial clay 


Pcrcentftsc of 

loss for 

c!ntlre block. 


VorcentHgc of 

cachconstltucnl 

saved. 


rercentago of 

each eunstltu- 

enl lost. 


.SiO, 


44. Li^ 


•■ii.n% 


'ir,.Z4% 


42.4:5^ 


.^)7. .')7 


AljOj 


30. S4 


.S!1.90 


0.00 


100.00 


0.00 


KeO 1 












Fe,0, , 


14.ST 


17.(11 


1.2:! 


01.22 


8.78 


CilO 


0.48 


None. 


0.48 


0.00 


100.00 


MifO 


o.a- 


0.25 


0.08 


71. S4 


2X.ir, 


K,0 


4.a6 


1.'.'4 


:i.:^H 


22. 04 


77.9.5 


Na,() 


0..5I 


0.2:5 


0.:« 


0.30 


O'.I.IU 


C 












11,0 


4.4!) 


16.62 


0.00 


lS7.:n 


None. 



0<).07<5; 100.02'? 40.8:!(s; 

.Microscopical and physical examinations are even more important 
tlian chemical analyses in determining the stal)ility of roofing slates 
wliicli cx]iosc such a relatively large surface^ to the action of frost and 
solution. Merrill has based his discussion of the stability of slates 
upon the amount of crystallization as shown by the microscope and the 
presence or absence of free carbonates of lime and magnesia, sulphides 
of iron or of carbonaceous material. The most characteristic features 
of the microscopic structure of the Peach Bottom slates are as follows: 

The most evident constituents ai"e quartz, feldspar and chlorite. 
These are very small and indistinctly outlined against each other, as 
is usual in fine-grained slates. In the preparation of the slide the 
fibrous character of tlie stone which is evident upon larger pieces is 
especially prominent, and this is not wlidlly lost in even the thinnest 
parts of the slide. The material seems to be completely recrystallized 



228 A HISTORY OF THE QUARRYING INDUSTRY 

and no constituent is present in large areas which is at all untrust- 
worthy. As the color seems to come from the chlorite and not from 
the finely comminuted particles of non-crystalline material, it should 
be permanent and unfading. 

Professor Mansfield Merriman," who has made a long series of ex- 
periments on the best methods of determining the durability of slates, 
regards physical and impact tests as most expressive of their perma- 
nency. An account of his experiments on the Peach Bottom slates is 
as follows : " During the present year the writer has made tests for 
strength, toughness, density, softness, porosity and corrodibility on 
twelve specimens of Peach Bottom slate, following the same methods 
as described in the former paper for the old Bangor and Albion slates. 
The specimens were 12 x 24 ins. in size, varying in thickness from 
0.21 to 0.29 in. For the test of strength they were laid on supports 
22 ins. apart and broken by a load slowly applied at the middle. The 
modulus of rupture for each case was then computed from the formula : 

,, , , 3 X breaking load x length 

Modulus = " ? 

3 X width X square or thickness 

" For instance, the specimen marked Qi was 12.04 ins. wide, 22 ins. 
between supports, 0.26 in. thick, and it broke under a load of 283^ 
lbs. ; hence its modulus of rupture is 11,490 lbs. per square inch. The 
deflection, measured at the moment of rupture, was also noted as an 
index of toughness. 

" The density of the specimens was determined by finding the spe- 
cific gravity of each. The degree of softness was found by the weight 
aliraded by 50 turns of a small grindstone under a constant pressure 
of 10 lbs. The porosity was determined by finding the percentage of 
water absorbed in 24 hours, after being dried for the same length of 
time at a temperature of 135° Fahr. The test for corrodibility was 
the percentage of loss in weight after immersion for 63 hours in a 
solution consisting of 98 parts by weight of water, 1 part of hydro- 
chloric, and 1 part of sulphuric acid. 

" The color of the slate was a dark bluish gray, or bluish black, and 
the texture of the surface was slightly scaly and soapy, being less 

'Trans. Amer. Soc. Civil Eng., vol. xxvii, 1893. pp. 3.S1-349; vol. xxxii, 1894, 
pp. 529-539. 



MARYLAND GEOLOGICAL SURVEY 



229 



smooth than the jSTorthampton varieties. AVhen ruptured by flexure, 
the specimens broke square across the grain without splitting or lami- 
nation. The tests for density, softness, porosity and corrodibility 
were made on pieces of the ruptured specimens. 

" The table below gives the results of all the tests for each of the 12 
specimens and also the mean values. 

" An examination of these results tends to confirm the conclusions 
announced in the previous jiaper that in general the strongest speci- 
mens are the heaviest and softest, as also the least porous and cor- 
rodible, although exceptions occur in the case of Q7 and P2, and the 
Q specimens seem more corrodible than the P's, although greater in 
strength. The tests for strength and corrodibility are probably those 
of greatest importance in forming an opinion regarding the value of 
the slate under actual conditions of service. The test for softness, 
althoiigh a good one for a single lot of specimens, may not serve to 
fairly compare lots tested at different times on accoimt of the varying 
conditions of the grindstone. 



Mark of 
'pecimen. 


MoUuliiB Of rui"- 
lure tn Ibti. 
per sq. in. 


rilimiile 
deflection 
in incties 
on sun- 
portsSslns 
apart. 


Sped lie 
Gravity. 


Grains 
abraded by 
50 turns of 

small 
Krindstone. 


Percent, of 

water 
absorbed 
inv*4 hours. 


Percent, of 

welfiiitlost 

68 hours In 

acid solution, 


Q, 


11,.590 


0.32 


2.886 


69 


0.265 


0.347 


Q, 


13,.58.5 


0.30 


2.907 


115 


0.197 


0.197 


Q, 


S,400 


0.30 


2.900 


110 


0.304 


0.291 


Q. 


i;^,43() 


0.32 


2.893 


177 


0.228 


0.194 


Q. 


s,:«o 


0.28 


2.900 


75 


0. 264 


11.237 


Qo 


12,010 


0.32 


2.918 


67 


0.209 


0.300 


Q, 


14,210 




2.890 


111 


0.278 


0.341 


Q. 


13,0I!0 


0.34 


2.902 


t;7 


0.261 


0.240 


P. 


10,.520 


0.24 


2.912 


69 


0.171 


0.150 


P, 


9,300 


0.20 


3.88.5 


.53 


0.143 


0.336 


P, 


10,470 


0.34 


3.858 


87 


0.316 


0.161 


P. 


11,2.55 


0.26 


2.873 


80 


0.155 


.... 



Means. 



11,260 



0.293 



2.894 



0.224 



0.226 



.... While the preceding methods of testing are readily carried on 
in the laboratory, they are not easily made under conditions of actual 
practice on account of the absence of precise weighing apparatus, and 
the lack of time and skill. It seems desirable that a test for slate 
should be devised which can be quickly applied by an architect or 
builder, and be used with confidence. An impact test, made by simply 



230 



A HISTORY OF THE QUARRYING INDCSTRY" 



dropping a ball, appeared one likely to yield good results, and accord- 
ingly a series of experiments has been carried on to determine what 
can be done in this direction. In connection with these, a series of 

severe acid tests has been made on the same specimens The 

pieces of slate used in the impact test were 6 x 7f ins. Each piece 
was placed with the ends loosely clamped in grooved supports, so that 
it was approximately in the condition of a beam with fixed ends, the 
length between edges of supports being about 7|- ins. and the width 
6 ins. A wooden ball weighing 15.7 oz. was dropped upon the middle 
of the slate from a height of 9 ins., and the number of blows required 
to produce rupture was noted. The number of foot-pounds of work 
per pound of slate, expended in causing rupture, is a measure of the 
ultimate resilience of the material or of its capacity to resist shock, 
and thus is an index, both of its strength and toughness. Five speci- 
mens of each kind of slate were thus tested, and the table below gives 
the indi^adual results and means. ... As the resiilt of the investi- 



SpeciniL'u. 


Thickness 
inches. 




Weight 
ounces. 


No. of blows. 


Foot-pounds of 

worii per 
pound of slate. 


p. 


0.36 




17.3 


9 


0.13 


p> 


0.36 




17.3 


15 


10.39 


Ps 


Q.31 




20.4 


5.5 


31.74 


p< 


0.38 




18.4 


53 


.33.35 


pp. 


0.39 




20.4 


68 


39.33 


Means 


0.3S 




18.7 


39.8 


34.17 


Q, 


0.36 




17.3 


11- 


7. .54 


Q. 


0.27 




17.8 


30 


13.35 


Qs 


0.3'.l 




19.3 


17 


10.39 


Q. 


0.38 




18.3 


6 


3. 89 


QQ, 


0.37 




17.6 


11 


7.37 














.Means 


0.37 




IS.O 


13.0 


8.49 




Percentages ofloss of weight. 


Foot-pounds of 

worl; per 
pound ot slate. 




Spec. 


After 
lao hours. 


After 
240 hours. 


After 
.%fl hours. 


Specific 
gravity. 


Q, 


0.4.5 


0.90 


1.37 






Qa 


II. +11 


0.99 


1.33 






Mean 


0.43 


0.94 


1.39 


8.5 


3.90 ■ 


Ps 


0.33 


0.81 


1.13 






P. 


0.38 


0.9S 


1.10 







Mean 



0.30 



0.87 



1.11 



3.89 



MARYLAND GEOLOGICAL SURVEY 231 

gations thus far made, it may be concluded tLat the tests for density 
and softness, although of importance for slates of the same locality, 
are not good indications of the strength and weathering qualities of 
those of different regions; that the tests for porosity, corrodibility and 
flexural strength give good indications of these properties; that the 
results found for strength and corrodibility when mentally combined 
give on the whole an excellent idea of the value of the slate; ami 
that an impact test with a wooden ball shows both strength and tough- 
ness, while it at the same time indicates the capacity for resistance 
to corrosion." 

LTAMSVILLE. 

At the present time no slate is quarried at Tjamsville, although this 
locality has been known as a source of slate for nearly, if not quite, a 
iiundred years. Parrish in his brief history of the slate trade in 
Ainerica states' that quarries " near Frederick " were opened about 
1812. This may be a reference to the small openings at Linganore, 
but it seems more in harmony with local traditions to infer that the 
quarries about Ijamsville were in mind. 

When Tyson prepared his report there were two slate quarries in 
operation. One was situated just west of the railroad station, beside 
the tracks, and the other was about a half mile south of the town. 
They were evidently quite small, for they had not reached the best 
mateiial. Little work was done during the time of the Civil War, 
and the more prominent quarry, shown in Plate XXIV, Fig. 2, was 
permanently abandoned about 1870, when the " pit " commenced to 
undermine the roadbed of the Baltimore and Ohio Railroad. The 
smaller opening, lying south of the town, never attained any con- 
siderable importance, although efforts were made as late as 1892 to 
bring the product of this quarrs' into the market. The method of 
working followed was that of the Germans, who mine rather than 
quarry their slate. A shaft was sunk to a depth of about sixty feet, 
but the enterprise was not successful. 

The slates from Ijamsville formerly brought nearly as good prices 

'.•\nier. Jour, iliniug-, ii, 1S66-T. 



232 A HISTOEY OF THE QUAREYING INDUSTRY' 

as those from Hai-ford county,' but at the present time they are almost 
imsaleable. This is not due to the poor or unstable character of the 
stone so much as it is to the relatively poor workmanship displayed 
in recent years and the popiilar demand for a slate which will ring 
when tapped with a finger or pencil. Because of the hard and com- 
pact character of the better siliceous slates from Pennsylvania and 
the northern states, it has become customary to regard all dull or soft 
slates as untrustworthy. In many instances this view is correct, but 
in the case of the Ijamsville slates it is not warranted by the facts. 
The slates from this locality show microscopically that they are well 
crystallized, and that they do not owe their softness to a partial change 
from a shale to a slate, but to an admixture of the relatively stable 
and soft mineral talc, which is usually wanting in the better known 
slates. If the stone were unstable the blue-black color would change 
upon exposure. This it does not do, since roofs on which the slates 
have been exposed to the atmosphere for fully fifty yeai-s do not 
indicate any change in color as a result of this exposure. In spite 
of their permanency in color and their strength the slates have yet 
to prove themselves a basis for a profitable industry. 

' The price per ton for the Harford county slates, as given by Tysou, 
ranged in 1860 from $12 to $23, whicli would be approximately from $1 to 
$6.50 per square. The prices for the Ijamsville slates were: " First quality, 
$5 for 560 lbs., which cover 100 square feet; second quality, $4 for 620 lbs., 
which cover 100 feet." The quality of the slates furnished was probably 
about equal to that of the Lehigh slates of to-day. 



jrARYLAKD GEOLOGICAL SIRVEY 233 



THE BUILDl^^G-STONE TJLVDE. 

Collection of Statistics. 

Any discussion of the statistics concerning the building-stone in- 
dustry in Maryland or any other state must be limited to conditions 
obtaining during the last ten or fifteen years, and even within these 
limits the figures obtained ai-e far from satisfactory. There is prob- 
ably no line of statistical work which offers a greater number of dis- 
couraging features in proportion to the problems involved than that 
connected with the quaiTying industries. These difficulties arise from 
several causes. Prior to the inauguration of statistical work by the 
U. S. Geological Sun-ey there seems to have been no attempt at the 
uniform collection of annual figures regarding the output of building 
stone within the limits of tlie United States. The only exceptions 
to this statement are found in the tables presented in the Eighth, 
Xinth and Tenth Census Keports made in the yeai-s 18G0, '70 and '80 
respectively. Earlier rejxirts of this nature either made no enumera- 
tion of the industry based on actually gathered statistics, or their 
classification is such as to render comparison with later data of little 
value. 

The work of the U. S. (Jeological Survey in the collection of sta- 
tistics has been noteworthy, and a marked increase in the amount of 
information concerning the building-stone industry is evident from 
year to year. The fii-st repoi-tri of this organization were based upon 
the Tenth Census, atid it was not until the yeai- ISSi that any con- 
siderable amount of material was collected concerning the granite 
industiy of the different states. At the beginning of their work the 
agents of the Federal Survey met with many discouragements which 
have been encountered anew in the prosecution of the present work. 
The greatest source of dtday and lack of details arises from the atti- 
tude of the quarrj'men themselves, who disregard written communi- 
cations and even refuse to impart information to membere of the 
Sur\'ey. The grounds for this attitude among the quarry-men arc 



234 A HISTOKY OF THE QUARRYING INDUSTRY 

due to various reasons. Sometimes no record lias been kept of the 
amount of the product which has been shipped, and in other instances 
the record preserved is in such shape that little of a statistical nature 
can be gathered. Among those operators who preserve a careful 
record of their output, expenses and wage list, there are many who 
refuse to give information because they have been so annoyed by the 
importunities of unauthorized gatherers of statistics, who make un- 
warranted requests on the time and information of the quarrymen, 
that they fail to make a discrimination between demands which are 
legitimate and those beyond all reasonable bounds. Many of the trade 
journals and similar organs have gathered statistics from year to year 
and published them in such a way that trouble has arisen between the 
employers and the employees, until the operators are almost afraid to 
give even the most commonplace information. Other statistics 
gathered from various soiirces have been utilized by the tax collectors 
and other petty officials as a basis for exorbitant demands, imtil the 
quarrymen feel that information may be used against them in almost 
any conceivable way. Before satisfactory statistics can be gathered 
concerning the various phases of the quarrying and marketing of 
stone, it will be necessary to overcome all of these misunderstandings 
and prejudicial notions held by the quarrymen. 

Annual Production in Maryland. 

Considering all of the available sources of information, of which 
the most trustworthy are the reports of the U. S. Geological Survey, 
it has been possible to construct the following table which approxi- 
mately represents the annual output of the quarries within the state 
during the years 1860 to 1897 inclusive. 

A study of these columns gives only an inadequate conception con- 
cerning the fluctuations of trade which have occurred during the last 
half century. So much depends upon the conditions under which 
the statistics were gathered and the minimum limit of output recorded 
that it is of little use to make a detailed study of the individual indiis- 
tries. There are, however, a few facts concerning the statistics 
obtained in different years as recorded by the various statistical 
bureaus which are of interest. 



MARYLAND GEOLOGICAL SURVEY 235 

VAI.IE l)F ANNUAL I'UODL CTION IN MARVLANI). 
Gkanite. Sandstone. Si.ate. Mahiu.e. Limestone. Total. 



LS60 


40, 900 




20,000 


30,000 


324,030 




1870 


8^,229 




80,8.53 


275,000 


234,199 




1S80 


224,000 




.50,700 


05,929 






1881 














1S82 














1883 














1884 






4.5,000 








iss.-, 






65,250 








ISSG 






54,000 








1887 






90,000 


10(1.110(1 


429,(1(10 




1888 


2(;:!,9.52 


[1.5, 000 1 


85,500 


175,000 


[175,000] 




1 8sil 


447,489 


10,60.5 


110,008 


119,675 


164,800 


872,778 


1890 


447,489 


10,00.5 


110,008 


139,810 


1G4,.800 


872,778 


1801 


4r.0,000 


10,000 


12,5,425 


100,000 


1.50,000 


83.5,425 


1892 


4;>0,0(I0 


,5,000 


116,.500 


105,000 


200,000 


807,-500 


1893 


2r.o,s.i.T 


300 


37,884 


130,000 






1894 


308,9Cili 


3,450 


153,068 


175,000 


350,000 


990,484 


189.5 


370, 020 


10,830 


00,357 


145,000 


20(»,000 


608,214 


1S9G1 


2.51,108 


10,713 


72,142 


11((,000 


204,278 


708,241 


1897 


188,33.5 


[10,000] 


.53,939 


100,000 


249,809 


608,083 



Granite. — Since the war the granite industry has shown a slight 
bnt steady increase in the amount of its output, which is not fully 
brought out by the increasing values of the annual product. The 
reason for sucli nn increase in volume seems to lie in the growing 
demand for granite in all sorts of structures and in the slight cheap- 
ening in the cost of extraction and dressing. These conditions are 
accentuated by the gradual change in public taste respecting the use 
of triuiiiiiiig stones, which demands gray sandstones and granites in 
place of the broAvnstones. The latter now hold a far less important 
position ill the market than in the years inmicdiatcly succeeding the 
Civil War. During these years there has also developed a consider- 
able trade in paving stones and road iiidals which has allowed the 
utilization of the angular blocks and waste of the quarries, thereby 
decreasing largely the ex[)ensc of operation. The trade seems to be 
moderately uniform and somewhat similar to the oscillations in the 
general demand, as, for examjile, in June, 1893, there was a marked 
falling off ill tbc output, the only shi])iii('iits being in fulfilluiciit of 

' See note p. 241. 



236 A HISTORY OF THE QUARRYING INDUSTRY 

I 

orders alreach^ presented. The trade recovered temporarily in 1894, 
but has since then been in even a more discouraging condition than 
at any time during the last decade. 

Sandstone. — The sandstone industry is the most variable among 
all of the quarrying industries carried on in the state. During the 
years 1875 to 1884, no work was carried on at the Seneca. This 
stagnation in business was due to the strong reaction against brown- 
stone and other sandstones which swept over the country about 15 
or 20 years ago. During the years 1888 to 1891 there was consider- 
able activity, but the sandstone industry felt the general depression 
of '93 so strongly that the reports indicate almost no output. Later, 
as tlie companies became active, the product increased somewhat and 
is at the present time about normal. In fact, there seems to be a 
slightly grcwing demand for high grade brownstone which may in 
time supersede the lighter colored stone as trimming. 

Marble.- — The marble industry has been almost constant through- 
out the last ten years, showing only slight relative changes in the value 
of the product, which averages about $140,000 annually. This is the 
only industry which did not seem to feel the depression of '93, a fact 
which is due no doubt to the uniform product and uniform demand 
for the Cockeysville marble, A\'hich furnishes most of the material 
within the state. Some of the fluctuations between the different years 
may be accounted for by the oscillations in the serpentine output, 
since this is included among the marbles. 

Slate. — The nearest complete details concerning the actual output 
of the quarries are available respecting the slates. This no doubt 
arises from the peculiar nature of the manufacture and the high skill 
and intelligence required in the preparation of slate stock for the 
market. Unlike that of the other bviilding stones, the manufacture 
of slate requires a special skill which is usually acquired by practice 
from childhood. This fact influences greatly the product of the vari- 
ous quarries, for it is regarded by the operator as more disastrous to 
discontinue operations than to be left with a surplus of stock. The 
labor, because of its peculiar skill, cannot be replaced at will, and the 
quarrymen throAvn out of their customary employment are unfitted to 



MARYLAND GEOLOGICAL SURVEY 237 

enijage in othrr linos of indnstrv. This method of procedure requires 
an increased capital, which in turn has rendered the profits much less 
during periods of depression,' since there is no compensating reduction 
in the wages of the quarrvmen. 

Prices, Wages, ktc. 

'Die facts which have heen gathered from personal conversation 
witli (luarivuicn and contractoi"s over the entire state are so at vari- 
ance with one another, especially concerning the price, that it has 
heen impossible to obtain any mean values which satisfactorily repre- 
sent the average price per foot for the different products throughout 
the state. AVith the exception of the highest grade work, and the 
product of one or two of the larger operators, there is no systematic 
regularity in the price charged for products of the same kind and 
quality, the prices even var\-ing 20 to 40 per cent on opposite sides 
of a hill connected by a deeply cut valley which eliminates variations 
due to differences in the price of hauling. The same fact is true 
concerning the gneisses quarried about the city of Baltimore, where 
the figures given for different quarries show a variation in the price of 
random rubble, for example, of fully l.')0 to 200 per cent. The 
prices for the different products are given in subjoined tables, from 
which it u)ay be seen that the same material when sold by different 
standards is really sold at quite different prices, as, for example, when 
rul)ble-gneiss is sold at the rate of $2 a cubic yard ($1.38 per jwreh), 
$1 per long ton ($.74 per perch) and $1 per perch. The figures 
gathered likewise do not show a uniform difference in price between 
the labor and the product in the counties and those in the vicinity of 
Baltimore, although the price is usually lower in the country districts 
for both, except among the skilled laborers belonging to unions which 
regulate the wages. Even here at times tliere seems to be an unfair- 
ness toward the city artisan, since he is compelled to pay somewhat 
more for living expenses than his competitor outside nf urban in- 
fluences. 

The actual information in these tables is limited by the confidential 
nature of the facts given and the unwillingness in certain instances 
to impart any sort of statistics because of previous breaches in con- 



238 A HISTORY OF THE QUAKKYING INDUSTRY 

fiflenee by unofficial agencies. The wages are generally fixed l)y the 
unions to which most of the skilled workmen belong. Considerinc: 
the capital invested, the wear of machinery and the valnc of the 
stone in the ledge, the margin between the cost of extraction and the 
price of the finished product is not excessive. 

GRANITE AND <4XEISS. 
Undressed Stone. Cost Wages. Prices at Quarry. 



Per foot. Koyaltyper DreSS- S- L- Per Per Per Per 

" '""'•• percli. perch. vd. cu. Ir. ton M 

I «(i. 

Rubble $3..50 $1.00 ... .«l.on 

1.80 

Flagging W . . 

35 . . 

Curbing ... .30 . , 

Paving ... .2.5 ., 



.30 



Belgian blocks $10 peril 

Dimension .60-1.3.5 

Monumental .70-1.35 

Rubble 05 3.00 1.00 .80 3.00 

1.35 1.50 

Flagging .3] 28 

56 

Curbing 6-10 35 

60 

Coiling S 45 

3.00 



Dimension .... 3.50 1.50 

Pointed .... 3.00 1.35 65 . 

75 . 

Ax bammered 13-15 65 . 

1,50 . 

Bush liammered 33-33 1.03 . 

Belgian bloeks .^lOper M 1.80 30 $i, 

5 

TRIASSIC SANDSTONE. 

Cost of Undressed 

Stone. IVages. 



Cu. ft. Royalty per 

percli. 



Rubble 00— $1.50 .35 $3.50 $1.35 

.3.00 1.35 



-MAKYLAXD GEOLOGICAL SVKVEV ^JJU 

PALEOZOIC SANDSTONE. 

Cost hf Lndhkssed 

Stone. Waues. 

^ . I.. 

Rubble .$1.00— .$3.00 per cu. yd. .$l.:i.T— .$1.4.-> *l.w'.5 

Flaggiug 1.4.5 per sq. yd .... 

Macadam .70 per percli .... 

Tlie wages in Alli'nanv and Garrett counties are lower than in 
IMontgomery and Frederick since the industry in the latter localities 
is more firmly established and the product of a higher grade. 'J'lie 
variations in price for the same material according to the units of 
measurement are noticeable in the sandstone reports, but they are not 
so extreme as in the gneiss and granites. 

All of the product of the Peach Bottom area is used for roofing 
slates, since the grain of the rock is rather against its being used for 
milling purposes. Thus the above prices represent the figures for 
almost the entire output of the region. The slate trade maintains 
the price of stock more uniformly than almost any other of the stone 
quarrying industries, for the prices obtained to-day are nearly tlu; 
same as those obtained seventy-five or eighty years ago. The method 
of reckoning has changed from weight to area of roof, and the " lap " 
of the upper courses of the latter has during the years increased from 
two to three inches in the higher grade materials. The manner of 
estimating the number of pieces per square is based on the practice 
in laying slates. The slates are laid so that the first course is over- 
lain by the second course and by two or three inches of the third. 
The overlapping of the first third coui'ses is known as the " lap," and 
it is not unusual for the roofer to buy his stock with a " three-inch 
lap " and lay it with only a " two-inch lap," thereby saving for him- 
self a small margin which does not appear to the consumer. More- 
over, the workmanship and uniformity in the product has greatly 
improved so that, although the apparent price remains the same, 
there has been a steady improvement in the material furnished to the 
consumei'. 

The following list of prices does not repi'esent anj' except the 
standard thickness of three-sixteenilis inches. That is, the stock 
runs about four pieces to the inch " in ilic rick."' When the speci- 



240 



A HISTOEY OF THE QUAEEYING INDUSTEY 



Mu. & Pa. 

Slates. 



SLATES. 
Pa. Slates. 



Maine 

Slates. 



Vermont 

Slates. 



9x7 


686 














3.. 50 


3.. 50 








lOx.5 


833 


3.05 


3.35 




















10x6 


686 


3. .50 


3.. 50 
















7.00 




lOxT 


596 


3. .50 


3. .50 
















7.00 




10x8 


514 


3.50 


3. .50 










4.00 


3.00 




7.00 




11x5 


730 


3.35 


3.50 




















11x6 


600 


3.65 


3.75 




















11x7 


514 


3.65 


3.75 




















11x8 


450 


3.65 


3.75 










4. .50 


3.. 50 








13x6 


534 


4.50 


4.75 


3.30 


3.10 


3. .55 




4.80 


3.80 


4.00 


9.00 




13x7 


458 


4.60 


4.75 


3.35 


3.20 


3. .55 




.5.00 


4.00 


4.00 


9. .50 




13x8 


400 


4.60 


4.75 


3.35 


3.25 


3.55 




.5. .50 


4. .50 


4.00 


9. .50 




12x9 


356 


4.60 


4.75 










5.60 


4.60 


4.00 


9.50 




12x10 


330 


4.60 


4.75 










.5.80 


4.80 


4.00 






14x7 


374 


4.85 


5.35 


3. .50 


3.40 


3.95 




6.40 


5.40 


4. .50 


11. 


3.60 


UxS 


338 


4.85 


5.25 


3.75 


O.40 


3.95 




6.60 


5. .50 


4. .50 


11. 


3.60 


14x9 


391 


4.85 


.5.25 


3.75 








6. .50 


5.. 50 


4. 25 


11. 


3.60 


14x10 


362 


5.00 


.5.25 










6.60 


.5.60 


4.25 


11. 


3.60 


14x13 


219 














6.50 


.5. .50 








14x14 


187 














7.00 


6.00 








16x8 


377 


.5.10 


5.(iO 


4.40 


3.75 


4.25 


3.00 


7.30 


6.30 


4. .50 


11. 


4.00 


16x9 


247 


5.10 


5.60 


4.40 


3.75 


4.35 




7.00 


6.00 


4. .50 


11. 


4.00 


16x10 


233 


.5.00 


.5.50 


4.40 


3.75 


4.25 




7.10 


6.10 


4.50 


11. 


4.00 


16x11 


302 


.5.00 


5.50 










6.90 


.5.90 


4.35 






16x13 


ISO 














6.80 


.5.80 


4.00 






16x16 


1 39 














7.00 


6.00 








18x9 


314 


.5.10 


5.60 


4.30 


3.75 


4.25 


3.00 


7.10 


6.10 


4. .50 


11. 


4.00 


18x10 


192 


5.10 


5.60 


4.30 


3.75 


4.35 




7.30 


6.20 


4.50 


11. 


4.00 


18x11 


175 


.5.00 


.5, .50 










7.00 


6.00 


4.25 






18x13 


160 


5.00 


.5. 50 










6.80 


5.80 


4.00 




3.60 


18x14 


137 














6. .50 


.5. .50 








30x10 


170 


.5.10 


5.60 


4.30 


3.75 


4.25 


3.00 


6.80 


.5.80 


4. 50 


11. 


4.00 


20x11 


1.54 


.5.00 


.5. .50 


4.30 








0.80 


5.80 


4.35 






30x13 


143 


.5.00 


5.50 


4.30 


3.. 50 


4.25 




fi.90 


.5.90 


4.35 




3.60 


20x13 


130 


5.00 


5.50 




















20x14 


131 


















4.00 






22x11 


138 


5.00 


5.. 50 


4.00 


3.35 


3.80 


3.00 


6.50 


.5. .50 


4.35 




3.60 


22x12 


137 




5.50 


4.00 


3.35 


3.80 




6.60 


5.60 


4.00 




3.60 


22x13 


116 




5. .50 




















32x14 


108 




.5.50 














4.00 






34x13 


115 


.5.00 


.5.50 


3.80 


3.25 


3.50 


3.00 


(;.60 


.5.60 


4.00 




3.60 


34x13 


105 


4.85 


.5.35 


3.80 


















34x14 


98 


4.85 


.5.35 


3.80 




3.45 




6.10 


5.10 


4.00 




3.60 


24x15 


91 


4.75 


.5.15 




















34x16 


85 


4.75 


5.15 





















MAEYLAND GEOLOGICAL SURVEY L'41 

tications call for one-quarter inch stock, sawed edges, polished sur- 
faces or boring and countersinking, the price increases somewhat per 
square according to the character of the work required. The Peach 
Bottom slates do not need to be drilled and countersunk as much as 
some of the more brittle slates from the northern states, since when 
punched, the hammer goes through, making a clean hole without any 
injurious flaking or spalling on the underside. 

The figures in the foregoing table show that there has been a de- 
crease in the prices obtained for the Maryland slates since 1895, and 
that the material from the New England quarries demand higher 
prices than that for Maryland, while the prices of the Virginia and 
Lehigh slates are lower. 

Note. — The figures indicating- tlie annual i)i-oduot for IH'.m are tliose pub- 
lished by the U. S. Geolog-ical Sui-veJ-. .\lthough tliey are different from the 
results obtained in the exhaustive investigations carried on by the State 
Geological Survey, they are more valuable for a comparative .study, since the 
conditions governing their collection and tabulation are more in accord 
with those existing in previous years. 



16 



itFe 06 




MARYLAND GEOLOGICAL SURVEY/ 

WM. BULLOCK CLARK, St*te GeoiO(.ist. 



THE 



BUILDING AND DECORATIVE STONES 



OF 



MARYLAND 




Containingf an 

Account of their Properties and Distribution* 



BY 



GEORGE P. MERRILL AND EDWARD B. MATHEWS. 



(Special Publication, Volume II. Part H.) 



THE JOHNS HOPKINS PRESS. 
Baltimore, October, I89S. 



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